a holies ee Pee Re von Srey i ae Sa Digitized by the Internet Archive in 2010 with funding from University of Toronto htto://www.archive.org/details/bulletinofmuseumO06harv . J l- . — 4 , x, i, ‘ ¢ j n . a . i i: | . ' . . i - ’ . we 4 \ ~> ‘ > _ ta v : ‘ 7 fF ' ’ i ae c pes “MUSEUM OF Fin voces ZOOLOGY BULLETIN OF THE ar { AT HARVARD COLLEGE, IN CAMBRIDGE. VOL. VI. Parr I.—fes.. i—11. CAMBRIDGE, MASS., U.S. A. 1879-1880. UNIVERSITY Press: Joun WiLson AND Son, CAMBRIDGE. 613'708 A ae CONT E iets PART IL. No. 1.—List of Dredging Stations occupied by the United States Coast Survey Steamers “ Bibb,” ‘ Hassler,” and “ Blake,” from 1867 to 1879. B. Perrce and C. P. Patrerson, Superintendents ‘ No. 2. — Ophiuride and Astrophytide of the “ ot Wie aca Expedition. By T. Lyman. Part II. (9 Plates.) . : ; : : ; No. 38. — Reports on the Dredging Operations of the United States Coast Sur- vey Steamer “Blake.” V. General Conclusions from a Preliminary Ex- amination of the Mollusca. By W. H. Datu No. 4.— Reports on the Dredging Operations of the United States Coast Sur- vey Steamer “ Blake.” VI. Report on the Corals and Antipatharia. By L. F. Pourtaes. (3 Plates.) 2 : : A ; : : No. 5. — The Ethmoid Bone in the Bats. By H. ALLEN No. 6.— On certain Species of Chelonioide. By S. Garman. No. 7.— Contributions to a Knowledge of the Tubular Jelly-Fishes. By J. W. Fewxes. (38 Plates.) , = . : : : No. 8. — Letter No. 4 to C. P. Patterson, Superintendent of the United States Coast Survey, on the Dredging Operations of the United States Coast Sur- vey Steamer “‘ Blake.” By A. Acassiz No. 9. — Reports on the Dredging Operations of the United States Coast Sur- vey Steamer “ Blake.” VII. Description of a Gravitating Trap for obtain- ing Specimens of Animal Life from Intermedial Ocean-Depths. By C. D. Si1gsBEE. (1 Plate.) A : ‘ : ah tt No. 10.— On some Points in the Structure of the Embryonic Zoéa. By W. Faxon. (2 double Plates.) . ; : No. 11.—New Species of Selachians in the Museum Collection. By S. GARMAN . PAGE 121 128 127 147 155 159 167 No. 1.— List of Dredging Stations occupied by the United States Coast Survey Steamers “Corwin,” “Bibb,” “Hassler,” and “Blake,” - from 1867 to 1879. BENJAMIN PEIRCE and CaRLite P. Pat- TERSON, Superintendents of the Coast Survey. THE following stations were occupied by the U.S. Coast Survey Steamer “Corwin,” Acting-Master R. Platt, U. 8. N., commanding, in 1867, in connection with a survey for a telegraph cable between Key West and Havana. The dredging operations were in charge of L. F. Pourtalés, Assist. U. S. Coast Survey. The expedition was cut short by the breaking out of yellow-fever on board. Date. Position. Depth. Locality. May 17 1 90-100 fms. 5m. 8.S8.W. of Sand Key, Fla. “ 24 2 270% 1.6 m. from Chorrera, Cuba. “« 95 3 350 © 27. a a 29 4 20: 1.6 m. ee 66 The dredgings in 1868 and 1869 were made on board the U. S. Coast Survey steamer “ Bibb,” Acting-Master R. Platt, U.S. N., commanding, by L. F. Pourtalés, Assist. U. S. Coast Survey. They are all comprised jn the Florida Straits between Tortugas and Cape Florida. (See U. 8S. Coast Survey, General Coast Chart No. X., Coast Survey Report for 1850.) 1868, No. of Dredging. Fms. Locality. April 23 2d position 195 Off Sombrero. 6 66 3d (73 115 6 “ May 1 7 111 “ ee (74 66 6 1 91 74 6c ce 6c 5 1 11 oe ‘cc 6e “cc 4 il 52 (43 “cc “ “ 3 183 « ‘6 66 6c 9 962 (74 “cc ¢e 66 1 51 7 “ 74 se 1 19 Off Bahia Honda. é ‘“ 4 75 «“ ‘“ é “ 5 95 “ ‘“ VOL. VI. — NO. 1. 1868, May 4 ac “ce “ 66 6c it bb “ce “ is ae 66 be 6 “e ec be ee 66 46 ac 66 46 66 4c sé +c 6 ge sty be 4e 4c “e &6. 66 66 g Lad 6e Lad 4c ee ee 46 4é a 66 6 ¢e &é 46 Lad ¢e oe ee 46 “ec 46 24 sé sc iad 74 46 6e $6 oe “11 sé ec ee “é iad sé sé zs sc se 46 ‘é sé “6 “6 ce BULLETIN . of Dredging. Fms. 6 105 7 100 9 119 10 128 11 176 12 324 13 418 1 16 3 43 4 55 5 75 6 83 7 98 8 94 9 100 1 sr 3 150 4 135 5 266 2 34 4 67 +) 80 6 93 é 96 8 101 9 106 10 106 11 116 12 123 13 125 14 125 16 139 ily 147 18 298 19 237 2 26 3 54 4 67 5 82 6 94 7 103 9 119 10 119 11 128 OF THE Off Bahia Honda. Locality. 66 1868. May 1 66 ‘6 66 66 66 6é 66 66 66 66 “ec 66 sé 66 46 66 66 66 66 6c 66 66 66 “16 66 66 66 66 66 66 1869. Jan. 15 66 66 6é 66 “6 66 66 66 “« 16 66 66 66 66 66 6 66 ‘6 66 66 66 66 66 66 66 66 66 66 66 66 i Fe 66 66 66 66 oh odd 66 73 66 66 66 66 66 ce 6c 66 66 66 MUSEUM OF COMPARATIVE ZOOLOGY. No. of Dredging. 12 13 14 15 16 17 19 20 —_ SO MND OP &© | aw oo be — if ry bo & Cr GPa OO KH So we KH i) —_ i) Fms. 127 123 134 143 138 154 306 248 100 100 100 100 100 120 120 120 120 6-7 13 17 34 260 80-32 35 36 36 35 35 37 37 34 43 42 43 124 502 25 60 115 214 306 389 468 Off Locality. Sand Key. 66 W. of Tortugas. 66 66 66 oe No. of Dredging. 1 wondrF nF OH OAD OP & bo Several casts. oPowoNnDreeE NFP ARP WON RP OR WR OOP WN RB OD OT Oo bt BULLETIN OF THE Fms. 13 12-15 107 132 140 296 333 105 122 122 125 125 90 125 327 368 405 50 125 138 325 87 450 638 815 40 45 49 70 60 Locality. Between Rebecca Shoal Kast Key. S. of Rebecca Channel. 12m. W. of Marquesas. » Off the Quicksands. Off Marquesas. 66 66 S. of Marquesas. 66 66 66 66 Off Cojima, near Havana. Off Cruz del Padre, Cuba. and Off Double-headed Shot Keys. Off Conch Reef. Off French Reef. Off the Elbow Reef. 6 73 Off Carysfort Reef. MUSEUM OF COMPARATIVE ZOOLOGY. 1869. No. of Dredging. Fms. Locality. March 21 6 48 Off Carysfort Reef. 66 66 7 40 6c 6 ss 66 8 35 66 66 ae “ 9 12 Off Turtle Harbor. > ee 1 63 Off Carysfort Reef. 66 “6 2 116 “é 66 66 66 8 138 66 66 a A (Empty.) 293 “6 “6 66 ‘é 5 317 66 “6 rT rT 6 320 “ ‘6 = ae 7 351 <é i 6c 31 1 52 6é €é “6 66 ») 117 sé 66 ¢é eé 3 206 6é 6é A =¢ 4 349 “ ff April 1 2&3 9 Off Orange Key, Bahamas. se 3 1 15 Off French Reef. 6é ee 2 87 6é 6é 66 66 38 44. cé 6é ée¢ cé 4 6¢ 6é écé 6é 5 75 &é 6¢é 66 ¢é 6 10 66 cé - 21 1 135 Off Key West. 66 &é 2 995 66 6é - aa 3 140 “é oa es as 4 140 ae a 6é ¢é 5 120 6é 66 May 7 1 vA Off Tennessee Reef. 66 66 2 53 6e 66 66 ce 3 85 66 66 6é 6é 4 108 66 66 ée 66 5 114 66 66 66é ¢é 6 115 66 rz 4 es iy 7 124 vhs oa as a 8 160 ue be 6c ce 9 174 66 sé a se 10 200 «4 bi ee 8 2 41 Off Alligator Reef. 6 sé 3 53 ‘a4 74 é¢ 66 4 68 66 6é * 5 79 Gs “6 6é 6¢ 6 88 éé ee es Gs 7 110 “ af 66 (79 8 110 6é 66 6 BULLETIN OF THE 1869. No. of Dredging. Fms. Locality. May 8 9 ' 113 Off Alligator Reef. sé 66 10 118 66 3 “cc RGei ilk 138 66 66 ‘6 “cc 12 147 66 T3 é ‘6 13 156 66 rT; TL 14 189 “ “ ie 15 238 « z anny 3 | 1 30 Off Conch Reef. 66 66 2 39 66 66 sé 66 3 49 66 66 66 6c 4 60 66 66 &é 66 5 Yh 66 6¢ sc se 6 1 by / 66 66 sé 6 7 139 66é ce sc 66 8 157 66 66 bc 3 9 169 6< <3 “6 66 10 957 3 6c Eo ae 1 30 Off Pacific Reef. és éé 2 49 6s 66 «sé eé 3 60 66 66 6 “ 4 75 Te rT 66 6 5 98 ‘6 6c « és 6 180 ; “ ‘c 66 66 7 233 rT; 66 66 66 8 283 66 66 6¢ 66 9 987 66 66 The following dredging stations were occupied by the U. S. Coast Survey steamer “ Hassler,” Lieut.-Commander P. R. Johnson, U.S. N., commanding, during her voyage from Boston to San Francisco, in 1871 and 1872. Prof. L. Agassiz was in charge of the scientific department ; the dredgings were made by L. F. Pourtales, Assist. U. 8. Coast Survey. No. of 1871. Dredging. ° Fms. Locality. Dec. 29 1-4 75-100 Off Sandy Bay, Barbados. a) -90 5-8 17-100 “6 as 1872. Jan. 18 9 15 Lat. 11° 49’ S., between the meridians ae a 10 17 of 37° 10’ and 37° 27’ W., standing “6 “6 11 40 off and on shore. (74 é 19 500 6c 6é <6 “é 46 13 20 “é 6c¢ éé «é 6 14 75D (74 6é 66 sé ac 15 200 66 66 66 MUSEUM OF COMPARATIVE ZOOLOGY. Wi No. of 1872. ae al Fms. Jan. 20 16 30 ‘cc ‘é 17 20 73 sc 18 26 66 éé 19 44 As 22 20 35 ‘6 rT 91 45 Feb. 20 22 70 ‘6 ss 23 70 ‘6 22 24 19 as 29 25 7 March 1 26 44 6s 3 27 30 “ec 4 98 1 6é 66 99 95 “ 7 30 30 a 9 31 55 66 TI 82 57 6¢ 12 33 58 66 13 34 22 ag 19 35 13 ee 20 36 6 al 37 - 27 38 135 April 16 39 7-9 ee 25 40 35 66 66 Al 64 66 66 42 66 66 “< 43 84 ” a7 44 2410 ne 29 45 656 ws - 46 1144 May 2 47 65 66 ds 48 220 bi 13 49 45 Locality. Off the Abrolhos, Brazil. 6s 66 66 66 66 6é 66 66 66 Off Cape Frio, Brazil. 66 66 66 Lat. 32° 0’ S., Long. 50° 15’ W. 6é 66 “eé pant 34° 55’ S., Long. 54° 12’ W., off La Plata River. aos 35° 12/ §., Long. 55° 30’ W., in La Plata River. Lat. 37° 42’ S., Long. 56° 20’ W. By O39! ¢¢ 960° 35! cae baw Wi merrGa” sas vee? og ee. 63° 50! wm 8 ie tr 63> (hae 6 44°52! Ae 64° "10% oe. £9? 264 40/5) 66° BO" $69 FO SG" Ce DS 3 Naie Off Cape Possession, Patagonia. Anchorage at Sandy Point. is at Port Famine. & at Port Gallant. Between Sholl Harbor and Cape Tamar, Straits of Magellan. Talcahuano Bay. Off Talcahuano Bay. Surface temp., 57.5°. Bottom temp., 35°. Dredge lost. Two miles off Cumberland Bay, Juan Fernandez. Bottom temp., 39°. Three miles N. W. of Juan Fernan- dez. Bottom temperature, 36°. Off Cumberland Bay. 66 66 Off Valparaiso. "s 35° 29/ S., Long. 75° 11/ W. During the season of 1877 and 1878 the dredging operations from December to March were in charge of Alexander Agassiz, and the follow- 8 BULLETIN OF THE ing stations were occupied by the U. 8. Coast Survey steamer “ Blake,” Lieut.-Comm. C. D. Sigsbee, U.S. N., commanding. The cruise ex- tended from Key West to Havana, from Havana westward along the north coast of Cuba, from Key West to the Tortugas, thence to the northern extremity of the Yucatan Bank and Alacran Reef, to Cape Catoche and across to Cape San Antonio, returning to Key West, and from Key West to the Tortugas, and northward to the mouth of the Mississippi River. 1877-78. Temperature. Surface. Bottom. Locality. 73° 393° Off Morro Light. 77 ~=—-339$ = vi he 783 393 a, as (Bottom, soft coral ooze.) 774 39} 66 ‘6 66 sé 76 494 Lat. 24° 15’ N., Long. 82° 13’ W. (Soft coral ooze.) Liat.'24° 17’ 80” N., Long. 82° 9’ W. 7&8 (Only mud brought up.) Stat. Fms. 7. 801 2 805 8 924 4 936 229 5 152 6 137 9 ID 10. 231 95 80 61} “ ts Coarse sand and rock. 232 838° 80. 62 = 238 174 80 49} peor abe Rocky bottom. 234 306 803 47 Off Bequia. Very rough, fine gray sand. 2385 1507 79 89 ¢ S Light brown ooze. 236 1591 79 39 os e Fine gray ooze. 237 1290 384 Off Grenadines. V. f. sticky oz., brownish gray. 238 127 79% 56 “ as Fine coral sand. 239 338 80 454 us “ Fine sand and ooze. 240 164 793 523 ae - Coral and broken shells. 241 163 80 53 TT | 242 842 80 393 rs + Fine sand and gray ooze. “+ og il ED ee 244 792 72 89 Off Grenada. Gray ooze. 245. 1050. 7 39 i is Sticky fine br. blue ooze. 246 154 792 56 < as Fine gray ooze. 247 170 80 534 os me 248 161 80 533 “ a Fine gray ooze. 249 262 80 47 J es Coarse yellow sand. 250 421 80% 41} “ ae Coral sand and ooze. 251 382 80} 42 ‘* a Sand, little gray ooze. 252 306 80 444 Me Oe Gray ooze. 253 92 794 58% Hy ‘ Coral and broken shells. 254 164 78h 57 a - Coral and broken shells. 255 344 78 433 os od Dark gray ooze. 256 370 80 44% “ ss Fine sand and blue gr. ooze. ang" 58:80 AOR ete s58° "too 80° BoE es | 259 159 79k 53h“ « 260 291 794 47 us tf Fine gray ooze. - 261 340 1: 262 92 80 62 a * Fine sand. 263 159 80 58h * & 94 AIG 80 «42, * “ Gray ooze. 265 576 795 392 = Kg 266 461 80$ 414 “ « 267 626 81 394 si “ Light brown and gray ooze. 268 955 80 393 os si Gray ooze, rocky bottom. Stat. 269 270 271 272 - 273 , 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 Fms. 124 75 458 76 103 209 218 94 106 69 118 221 288 154 237 347 13- 399 713 200 137 180 123 120 140 Temperature. Surface. Bottom. 575° Off St. Vincent. 80° MUSEUM OF COMPARATIVE ZOOLOGY. 15 66 41h 643 59% 53h 52k 44h 40 703 493 74h 644 544 503 614 564 61 564 60 sé Locality. 66 Off Bequia. Off Barbados. 66 ée¢ Nature of Bottom. ~ Fine sand. Coarse sand & shells, hard bot. Coral & broken shells, yellow. Fine sand and ooze. Fine sand, brown specks. Hard rocky bottom. Coral bottom. Very rough, very rocky bot. Glob. sand. Glob. ooze and broken shells. Coral sand and broken shells. Hard bottom. Fine s, glob. ooze. Coral sand and broken shells. Hard bottom. Coarse coral s., broken shells. Flat cale. stones. Coral sand and broken shells. 66 66 66 Hard bottom. Cale. stones. Broken shells and coral. Coral and corallines. 7 ay Gs _o sth. 4 yore das us Ta. oS. rar ahh eas ie atl q se ad b k ae q Nay bi th t cy. ‘ d ¥ ant ~ he) ih : v™ re.) ‘* } ee a Way : i Panter ine. : ; i) ale y re P rt Mi ra ie \ ‘ , : ee Ps : - , : e a ne ‘ F ‘ : aa! < | ee te waliam nai lle La = .. en . - ‘S vey tea ner ; vu saiichaak helt NO EE a ee: per elisa dragged), | ia ae Bi): Ga, ae Aegis wes Mita ae. | pga, Te i ay . “ awe, sy ‘a (ie ‘ ‘ Haneunie oh lala Seed ae re Dh ee ay ee) oa ooo Na oy ie = ; A id , “4, aie (poe i y omg hogar aes ‘ Hey Dike al ao a et ee ry a: Le - lupe Se “ ; pe e oa ae > hei east we, tae j ‘ ry d ; ry : ore? agains SM a ey cig salve bara outa : sce wt ee ih ih eee Me a oe. Shaye Aen? 4 “" HS hth Talal — Ble Hite OSB.” * Oe: Oe aan gael Licgs Awe TD: |) Os ae Een a n 5) qv : "as A b fog: tt i . aa j Ping or Oe RE iA eee ass eit oss NS ey Meee HP ee oe ae ; A P . : ; . oe + ; 7 we hay ts‘ae . eae Bae Be pate Byes oN ge ear o. ae = 4 } te ? on. S > a 4 ae - U } he he i 7 M . f ‘ ' : ~*~ Oe . 7 ‘ 1 ¥ 7 - ERR «EES SRE INE, Ai i - ' tg ‘Av riaeth ale oil r An ese emiee) Silvis) Wate te %, 20%) eM pda aoe .; peas on Peer rhe , tae x . . - s . eo ‘ ; femal teas ‘1 - - ea) A ba ‘ Ww a ts i Ta j F< soe a) ‘—@r ' iy yy ‘ i ; a a AY! tes I] + - 4 te | A af ‘ “Mint 1 a : ru . oe 3 ; ab, = | oad 2° gle * A i -* ses 1 i * * No. 2.—Ophiuride and Astrophytide of the Exploring Voyage of H. M. S. “ Challenger,’ under Pror. Sik WYVILLE THOMSON, F.R.S. By THropore Lyman. PART IT. (Published by permission of the LorDs COMMISSIONERS OF THE. TREASURY.) Turs concluding portion of the Prodrome contains the Ophiuride not included in Part I, and the Astrophytide. There are two new genera and sixty-three new species: Amphiura, 19 species ; Ophiocnida, 2; Amphilepis, 3; Ophiactis, 7; Ophiostigma, 1; Ophiopholis, 1; Ophiochondrus, 1; Ophioconis, 2; Ophiomyces, 2 ; Pectinura, 2; Ophiopeza, 1; Ophiothrix, 4. Also of the genera already treated, there have since been detected in Ophiochiton and Ophioglypha one new species each ; and in Ophiacantha, four. Of Astrophytidee there are, Astroclon, 1 species; Astrotoma, 1; Astroceras, 1; Astroschema, 5; Ophiocreas, 4. There is added an index of the species contained in the two parts, to- gether with such other species from considerable depths as I have from time to time described ; the whole forming a list of the greater portion of the deep-sea Ophiurans and Astrophytons now known. CAMBRIDGE, Mass., December 25, 1879. VOL. VI. — NO. 2. 2 18 BULLETIN OF THE Disk-scales swollen, humpvy, and irregu- lar. ‘Ten stout, sharp arm-spines. Basal mouth-papillze wide and scale-like. Ten- jor scales very large, one overlapping the other, maxima. Four straight, tapering arm-spines. Disk-scales delicate. Upper arm-plates Radial shields | thin. aero about } Radial shields smalland ree times as nearly or quite separated. : j long as wide. {Seven or eight d | bellis. blunt, crowded, thick ¢ ‘4% arm-spines. Outer mouth- papilla scale-like. Radial shields very small, broad, about twice as long as wide. Five or six short, conical, barred spines. Upper arm-plates narrow and rounded. Radial shields broad, about twice as long AMPHIURA. TABLE OF SPECIES HEREIN DESCRIBED.. as wide. Three or four short, moderately | Raat arm-spines. Tentacle-scale minute. : Two tentacle- scales. Disk distinctly scaled on both argentea, | Radiat shields and upper arm-plates wider 4 —-——— >, a acacia. 8 cale. ( Six short, stout arm- spines. Disk- scales fine. Radial shields | Upper arm-plates narrow. narrow, about} our long, cylindrical ) thrice as long } arm-spines, the uppermost | as wide. and lowest longest. Ten- | iris. constricta, tacle-scale large and rounded. Four tapering, equal arm-spines. ae scales rather large and spaced. bed ha od No tentacle- scale. Two (sometimes : 2 . ) one) minute ten- Five slender, tapering arm-spines. Under -ple ‘ i ield-shaped. Outer tacle-scales. Ra- 2 °t™ plates squarish shie P + lanceolata, dial shields long pee ah ep spiniform. Upper arm-plates One _tentacle- than in A. Stimpsoni. 4 Two mouth-papille on each side. (O. mazima has a third rudimentary.) Disk below en and narrow, : or with rudimen- Five tapering arm-spines. Mouth-shields } tary scales. One well-mark- | wide. ed tentacle-scale. 1 Four or five tapering cylindrical arm- spines. Mouth-shields rounded. No _ tentacle- Radial shield pear-seed shape. Four to } dilkteam: glatra, } angularis. scale. five small, widely-spaced arm-spines. Th sath ill Two tentacle-scales. Fourarm-spines. Inner mouth-papillz Tee mouth-papiile ? thick; two outer smalland sharp. Radial shields narrow and § concolor. on each side. separated. Disk-scales fine; only central primary plate con- dalee. Three arm- | spicuous. First under spines, the { arm-plate small. middle one Disk-scales coarse; all oe ese swelled. primary plates conspicu- ( ua, i scale. ous. First under arm-plate —, ap aa a j wide and large. = co sgameapanea Four arm-spines. Disk naked below. Tentacle-scale minute and like alip. Ra- dial shields long and narrow, diverging inward. No tentacle-scale. Four arm-spines. Disk sealed on both sides. Radial shields large, wide, and joined for half their | length. Primary plates conspicuous. Two tentacle-scales. Three middle mouth-papille longest. } Point of mouth-angle occupied by lowest tooth. One tentacle-scale. Mouth-papille squarish and crowded, Side mouth-shields large and wide. Disk-scales irregular, small, and crowded. glauca. Verrilli. canescens. on each side. Five mouth-papillez | patula. MUSEUM OF COMPARATIVE ZOOLOGY. 19 Amphiura maxima sp. nov. Plate XI. Figs. 278-281. Special Marks. — Disk covered on both sides with swollen, lumpy, irregular scales : ten stout, sharp arm-spines. Outer mouth-papille wide and scale-like. Two very large tentacle-scales, one overlapping the other. Description of an Individual (Station 188).— Diameter of disk 15 mm. Length of arm about 135 mm. Width of arm, close to disk, without spines, 2.5 mm. One very large square mouth-papilla on each side of the angle, and a pair much smaller and more rounded at the apex ; besides these, there may be distinguished a minute papilla outside the great flat one. Mouth-shields large, and much curved within, and prolonged by a rounded lobe without. Side mouth-shields very small, pear-seed shape, with the smaller end inward ; they occupy the inner lateral sides of the mouth-shield, and are widely separated. Under arm-plates four-sided, broader than long, outer and inner edge slightly curved, and with feeble re-entering curves on the lateral sides. Side arm-plates short and high, scarcely prominent, meeting neither above nor below. Upper arm-plates small, little swollen, nearly round ; but some distance out on the arm they are broader than long. Disk round, flat, and rather thick, having a notch over each arm ; surface covered above and below with rather large, rounded, swollen, loosely overlapping scales, those in the interbrachial spaces being slightly larger. Radial shields pear-seed shape, little swollen, with a peak in- ward, separated their entire length by a row of three elongated scales, the inner one being surrounded by several much smaller. On the outer edge of the radial shields there is a row of small scales continuous with those on the margin of the disk. There are ten stout, pointed arm-spines, the two lowest being about twice as long as the others, much sharper, and usually curved. Two very large, flat tentacle-scales with curved edges, one on the inner margin of the tentacle- pore, which overlaps the one on the edge of the under arm-plate. Color in alcohol, straw. Station 188, 28 fathoms, 2 specimens. Amphiura bellis sp. nov. Special Marks. — Disk covered above and below with delicate scales ; two tentacle-scales. Radial shields narrow, about three times as long as wide ; four straight tapering arm-spines ; upper arm-plates thin. Description of an Indwidual (Station 232). — Diameter of disk 7 mm. Arm long, slender, and tapering gradually ; its width next the disk is 1mm. One stout, short, blunt papilla on either side of the base of mouth-angle, and a pair, stout and bluntly pointed, at its apex. The tentacle-scales of the first pair are spiniform and rather conspicuous. Mouth-shields small and rounded, with sometimes a rounded angle within and a slight lobe without. Side mouth- shields three-sided, quite broad without, tapering within, where they do not meet. First under arm-plate six-sided and rather larger than usual ; those 20 BULLETIN OF THE beyond squarish, about as long as broad, with outer side nearly straight, lateral sides a little re-enteringly curved, and usually a very short truncated angle within. Side arm-plates small, and not strongly projecting, meeting neither above nor below. Upper arm-plates thin, of a pretty regular transverse oval shape, with lateral corners well rounded Disk rather thick, and slightly lobed, covered above and below with small, rather thin, overlapping, scales, among which the primaries are scarcely to be distinguished ; those near the margin and underneath are finest, being 9 or 10 in 1 mm. long. Radial shields long, narrow and pointed within ; length to breadth 2:.7; they are separated their whole length by a narrow wedge composed of scales longer than those of the neighboring disk. Four Ea stout, cylindrical, tapering arm-spines, of equal lengths, and somewhat longer than the arm-joints. Two minute rounded tentacle-scales, one on the side arm-plate, the other on the under arm-plate. Color in alcohol, very pale brown. ‘The young of this species has sometimes only one tentacle-scale. Station 232, 345 fathoms, 9 specimens. Station 174 (var. ?), 210-610 fath- oms, | specimen. Amphiura incana sp. nov. Plate XI. Figs. 285-287. Special Marks. — Disk scaled on both sides. Two tentacle-scales. Radial shields narrow, about three times as long as wide, nearly or quite separated. Lower scaling coarse. Seven or eight short, blunt, crowded, very thick arm- spines. Description of an Individual (Station, Simon’s Bay, Cape of Good Hope). — Diameter of disk 7 mm. Arms about 70 mm. Jong, and slender ; close to disk their width without spines is 1.3mm. One short wide curved papilla each side of mouth-angle, and a pair, stout and bluntly pointed, at the apex of the mouth- angle above ; the tentacle-scales of the first pair are conspicuous. Mouth-shields small, of a wide diamond-shape, with outer angle truncated. Side mouth-shields much longer than wide, tapering slightly within, where they nearly or quite meet ; outer ends much rounded. Under arm-plates nearly square, with rounded cor- ners, and outer edge a little re-enteringly curved. Side arm-plates rather thick but not prominent, meeting neither above nor below. Upper arm-plates small, narrow, squarish with rounded corners; narrow within, broader without. Disk round, not very thick, covered with thin, very small overlapping scales: on the upper surface there are 5 or 6 in the length of ! mm. Radial shields small, of a long pear-seed shape, with outer edge rounded, separated their entire length by a wedge of three rows of crowded, closely overlapping scales. Just outside the radial shields there are numerous fine scales. On the under surface of disk the scaling is much finer, there being about 12 in the length of amm. Eight very short, stout, broad, nearly equal flattened arm-spines ; the two upper spines are somewhat broader than the others. Two minute rounded tentacle-scales on the side arm-plate. Color in alcohol, pale straw. Station, Simon’s Bay, Cape of Good Hope, 10-20 fathoms, 12+ specimens. MUSEUM. OF COMPARATIVE ZOOLOGY. 21 Amphiura argentea sp: nov. Plate XI. Figs. 288-290. Special Marks. — Disk scaled on both sides. One tentacle-scale. Radial shields very small ; about twice as long as broad. Five or six short, conical arm-spines. Upper arm-plates narrow and rounded. Description of an Individual (Station 171).— Diameter of disk 4mm. Length | “of arm about 22 mm. Width of arm near disk 1mm. One rather long, flat papilla on either side'of the base of the small, short mouth-angle, and a pair, much rounded, at apex. Scales of first pair of mouth-tentacles long and rather conspicuous. Mouth-shields much wider than long, rounded, with a wide curve within, and outer side feebly curved. Side mouth-shields very narrow within, -where they meet ; wider without. First under arm-plate small and narrow, being squeezed between the outer ends of the side mouth-shields ; those be- yond are as broad as long, bounded without by a clean curve, on lateral sides by slightly re-entering curves, and within by a truncated angle. Side arm- plates very short, so that there is a considerable naked space between them on the sides of the arm ; they stand well out, forming a strong spine-ridge. Upper arm-plates narrow, donger than broad, nearly pentagonal, with rounded corners and an angle inward. Disk delicate, covered above and below with minute, thin, nearly uniform, overlapping scales; 9 or 10 in the length of 1 mm. where they are smallest. Radial shields very small, slightly sunken, of a pear- seed shape, nearly or quite touching without, separated within by a narrow wedge of minute scales ; length to breadth .9:.3. Five or six short, nearly equal, stout arm-spines, whereof the lower are cylindrical and tapering, and the upper somewhat flattened and wider ; lengths to that of an under arm-plate, .6, .6, .5, .6, .6, .7,.4. Near tip of arm there are three long, sharp, and very slender spines, twice as long as the arm-joints: this so great variation of form is rare in Amphiura. One oval tentacle-scale. Color in alcohol, nearly white. Station 171, 600 fathoms, 1 specimen. Amphiura acacia sp. nov. Plate XI. Figs. 292-294. Special Marks. — Disk scaled on both sides. One minute tentacle-scale. Three short, moderately stout arm-spines. Radial shields short and wide. Description of an Individual (Station 235).— Diameter of disk 4.5mm. Length of arm, about 32mm. Width ofarm neardisk, 1mm. One flat rounded papilla on each side of the mouth-angle, and a pair, blunt and thicker, at the apex. Scales of the first pair of mouth-tentacles flat, and low down, so as to seem nearly on a level with the outer mouth-papilla. Mouth-shields small, rounded, longer than broad, widest without, and having a rounded point inward. Side rhouth- shields three-sided, short and broad, .widely separated within. Under arm- plates narrow, longer than broad, five-sided, with an angle within, outer side ae BULLETIN OF THE nearly straight, and lateral sides a little re-enteringly curved. Side arm-plates somewhat flaring, with a well-marked spine-ridge, meeting narrowly above and barely separated below. Upper arm-plates twice as broad as long, with a clean curve within and the outer side nearly straight, but having usually a feeble lobe in the centre. Disk rather thick, covered with fine, curved, rather thin, overlapping scales, which are largest in the centre, where may be distinguished an ill-marked rosette of primary plates ; thase near the margin are much finer (about 8 in the length of 1 mm.) : on the lower surface they become thinner and near the mouth-shield are hard to distinguish. Radial shields short and wide, curved on the interbrachial side, straight on the brachial ; barely touching without, separated within by a narrow wedge of four or five scales ; length to breadth, 1.1: .6. Three short, cylindrical, gently tapering, blunt, equal arm- spines about .5 mm. long. One minute, rounded tentacle-scale. Color in alco- hol, pale gray. Station 235, 565 fathoms, 3 specimens. Amphiura constricta sp. nov. Plate XI. Figs. 295-298. Special Marks. — Disk finely scaled on both sides. One tentacle-scale. Ra- dial shield narrow, about thrice as long as wide. Six short, stout arm-spines. Upper arm-plates narrow. Description of an Individual (Station, Port Jackson).— Diameter of disk, 5mm. Length of arm, 30mm. Width of arm near disk, 1 mm. One minute, rounded papilla at base of mouth-angle, on either side, and a pair, much larger, at the apex. Above may be seen the small scales of first mouth-tentacles, which resem- ble the outer mouth-papille. Mouth-shields wider than long, of a three-sided or wide heart-shape with rounded angles. Side mouth-shields long and narrow, especially within, where they do not meet. First under arm-plate small and very narrow ; those beyond are small and narrow, a little longer than wide, and four-sided with rounded corners ; they cover only a small portion of the un- der side of the arm. Side arm-plates small and not projecting. Upper arm- plates small and covering only a portion of the upper side ; pretty regular transverse oval, about twice as broad as long. Disk thick and somewhat puffed, covered with regular, small, rounded, overlapping scales, which are somewhat larger near the centre, where small round primary plates, widely separated by smaller scales, may be distinguished ; below and near margin of disk, the scaling is finer and more delicate, about 10 in the length of 1mm. Radial shields long, narrow, and slightly curved, acute within, separated their whole length by a wedge of many irregular scales of several sizes ; length to breadth, 1:.3. Six small, short, stout, blunt, peg-like, equal arm-spines about: .3mm., long, of which one or two are microscopically rough at theirends. The spines at tip of arm are similar, but proportionately longer. One rather large oval tentacle-scale. Station, Port Jackson, Australia, 2 to 10 fathoms, 1 specimen. MUSEUM OF COMPARATIVE ZOOLOGY. 2a Amphiura iris sp. nov. Plate XI. Figs. 302 - 304. Special Marks. — Disk scaled above and helow ; one large oval tentacle- scale: four long arm-spines, the uppermost and lowest longest. Description of an Individual (Station 236).— Diameter of disk 5 mm. Width of arm without spines 1.2mm. One short, stout, somewhat flattened blunt papilla on each side of the mouth-angle, and a pair, similar, but some- what smaller, at its apex. The large and broad scales of the first pair of tenta- cles are low down and conspicuous. Mouth-shields of a very wide heart-shape, much wider than long, with a rounded angle within. Side mouth-shields thick, long triangular, tapering inward where they do not meet. First under arm-plate usually large ; of a diamond shape, with its angles more or less trun- cated ; the plates beyond are longer than wide, with outer side curved and widest, lateral sides re-enteringly curved and a truncated angle within. Side arm-plates stout and rather prominent, meeting neither above nor below. Upper arm-plates fan-shaped, with inner angle more or less rounded, or trun- eated, and outer side gently curved. Disk covered above and below, with mod- erately coarse, crowded, irregular scales, those of the interbrachial spaces being more elongated, and those on the under surface somewhat obscured by skin. Toward the centre of the disk there are 7 or 8 scales in the length of 1 mm. Radial shields much longer than wide, slightly curved, somewhat swollen, tapering at both ends and widest in the middle ; separated their whole length by a row of three or four large scales; length to breadth, 2:.6. Four long, cylindrical, tapering arm-spines, whereof the uppermost and lowest are long- est, and equal to 1% arm-joints. One large tentacle-scale. Color in alcohol, pale gray. Station 236, 420-775 fathoms, 1 specimen. Amphiura tomentosa sp. nov. Special Marks.— Disk scaled on both sides with rather large, spaced scales ; those below somewhat obscured by thick skin ; four tapering, equal arm-spines ; no tentacle-scale. Description of an Individual (Station, Balfour Bay, Kerguelen Isl.).— Diam- eter of disk 6.5 mm. Width of arm close to disk, without spines, 1mm. One very small short mouth-papilla, often obscured by skin, on each side of the mouth-angle, and a pair, larger and rounded, at the apex. Mouth-shields irregu- lar, small, rounded triangular, with a small peak inward. Side mouth-shields longer than broad, wider without than within, where they just meet ; both they and the mouth-shields are somewhat obscured by skin. Under arm-plates narrow, longer than broad, pentagonal, with a blunt angle inward, small re- entering curves on the lateral sides, and outer lateral corners rounded. Side 24 BULLETIN OF THE arm-plates moderately projecting, nearly meeting above and below. Upper arm-plates somewhat broader than long, transverse oval, with a deep curve within, and a gentler one without. Disk thick and round, covered with thin, rather large, rounded scales, which are seldom overlapping, and often separated from each other by much smaller ones. Radial shields small, quite narrow, much wider without than within, where they form a sharp angle, widely sepa- rated by a wedge of three or four scales. The interbrachial space on the under surface is covered by fine scaling, which is often quite obscured near the mouth- shields by skin. Four equal, rather long, stout, and blantly pointed arm- spines.” Large round tentacle-pores, but no scales. Color in alcohol, pale gray. Station, Balfour Bay, Kerguelen Isl., 20-60 fathoms, 1 specimen. Amphiura lanceolata sp. nov. Plate XI. Figs. 305-307. Special Marks. — Disk nearly or quite naked below. Two small tentacle- scales. Radial shields long and narrow. Five slender, tapering arm-spines. Upper arm-plates narrow. Under arm-plates squarish shield-shaped. Outer mouth-papilla spiniform. Description of an Individual (Station 169).— Diameter of disk 4mm. Arms long and slender, about .7 mm. wide at the base. One slender, sharply pointed mouth-papilla on each side of the mouth-angle, and a pair, short and much rounded, at the apex. Mouth-shield small, thick, nearly oval. Side mouth- shields three-sided, large and thick, as broad as long, curving round the inner angles of the mouth-shield, but not meeting within. Under arm-plates nar- row, longer than wide, pentagonal ‘in shape, with an obtuse, or truncated angle inward, outer edge nearly straight, and re-entering curves on the lateral sides. Side arm-plates not prominent, nearly meeting above and below. Upper arm- plates much rounded triangular, with angle inward. Disk flat, with deep con- strictions in the interbrachial spaces, The scaling of upper surface of disk is rounded and overlapping, and is much coarser in the centre, where also the six primary plates may be distinguished : near the margin there are from 8 to 10 scales in the length of 1 mm. Radial shields long and narrow, sharply pointed within ; joined without, where the ends are much rounded, and separated within by a wedge of five or six scales. Interbrachial space on the under surface naked, or with scattered, scarcely discernible scales. Five rather long, slender, cylindri- cal, tapering, equal arm-spines about .6 mm. long. Two small rounded tentacle- scales, one on the under arm-plate, and one on the side arm-plate. Color in alcohol, pale gray. Station 169, 700 fathoms, 1 specimen. MUSEUM OF COMPARATIVE ZOOLOGY. 25 Amphiura glabra sp. nov. Plate XI. Figs. 308 - 310. Special Marks. — Disk below naked. Mouth-shields wider than long. Five stout, tapering arm-spines. One tentacle-scale. . ¢ Description of an Individual (Station 214).— Diameter of disk 5mm. Length of arm about 20 mm. Width of arm close to disk, without spines,.8mm. One ‘stout mouth-papilla in shape of an elongated cone on each side, and a pair, thick and rounded, at the apex of the mouth-angle. Mouth-shields broader than long, rudely triangular, with outer edges much rounded, and a small peak within. Side mouth-shields small, longer than broad, wide without, tapering inward, where they do not quite meet. Under arm-plates narrow, longer than broad, squarish, with re-entering curves on the lateral sides, outer corners rounded, and often an obtuse truncated angle within. Side arm-plates of mod- erate size, and slightly flaring, meeting neither above nor below. Upper arm- plates somewhat arched, rudely triangular, with outer edge rounded, and a blunt angle within ; further out on the arm they become transverse oval. Disk flat and lobed, covered above with thin, rather indistinct scales; those in the centre coarser and more rounded; those in the interbrachial spaces narrower and more closely overlapping. Radial shields short pear-seed shape, longer than broad, separated their entire length by a narrow wedge-row of small scales. Interbrachial spaces on the under surface naked. Five rather stout, tapering arm-spines, somewhat longer than the arm-joints, placed close to- gether on the side arm-plate. One rather large round tentacle-scale near the inner angle of the under arm-plate. Color in alcohol, nearly white. Station 214, 500 fathoms, 1 specimen. This species is allied to A angularis, but has a finer build ; side arm-plates less prominent ; side mouth-shields smaller, and radial shields shorter and wider. Amphiura angularis, sp. nov. Special Marks. — Disk below naked, or with a few rudimentary scales. One well-marked tentacle-scale. Four or five tapering cylindrical arm-spines. Mouth-shields rounded. Description of an Individual (Station 150).— Diameter of disk 9mm. Length of arm 45 mm. Width of arm, without spines, close to disk, 1.2mm. One long, tapering, pointed mouth-papilla on each side, and a pair, short, blunt, and much rounded, at the apex of the mouth-angle. The tentacle-scale of the first pair is large and spiniform. Mouth-shields rather large, nearly circular, with a small peak within. Side mouth-shields large, three-sided, broad without, and curving downward about the mouth-shield, narrow and separated within. First under arm-plate very small and squarish ; those beyond are nearly square 26 BULLETIN OF THE and rather narrow, with outer corners rounded, and slight re-entering curves on the lateral sides. Side arm-plates wide, prominent, and much swollen along the spine-crest ; separated below, nearly or quite meeting above. Upper arm- plates transverse oval, much wider than long, with well-rounded lateral ends. Disk flat and angular, covered above with coarse, rounded, overlapping scales, the five primaries being but little larger than the other scales ; the scaling on the interbrachial spaces is finer than in the central portion. Radial shields much longer than broad, tapering towards each extremity, with the inner point acute, separated their entire length by two or three rows of irregular scales ; length to breadth 2:.7. The scales of the margin continue round the outer end of the radial shields. Interbrachial space below only about one third covered with minute scaling; the rest of the space is naked. Four stout, blunt, tapering, cylindrical arm-spines, evenly spaced on the side arm-plate. One stout, round tentacle-scale on the inner side of the tentacle-pore. Color in alcohol, disk gray, arms straw. Station 150, 150 fathoms, 12-+ specimens. Amphiura dilatata sp. nov. Plate XI. Figs. 314-316. Special Marks. — Disk naked below. Radial shields narrow pear-seed shape. Four or five small, widely spaced arm-spines. No tentacle-scales. Description of an Individual (Station 141). — Diameter of disk 5mm. Length of arm 23 mm. Width of same without spines, close to the disk,.7 mm. At the base of the mouth-angle, on each side, is a long, very slender mouth-papilla, and a pair, blunt and rounded, at the apex. Mouth-shield small, short diamond- shape, with much rounded angles. Side mouth-shields small and curved, narrow within, where they nearly or quite meet ; outer end wide club-shaped. Under arm-plates narrow, longer than broad, squarish, with re-entering curves on the lateral sides, and the outer edge nearly straight. Side arm-plates very small, not prominent, nearly or quite meeting above, separated below. Upper arm-plates transverse oval, with the inner curve stronger than the outer, and the lateral corners pointed ; there is a slight longitudinal ridge. Disk rather thick and slightly puffed; primary plates widely separated and scarcely to he distinguished from the general scaling, which is fine, regular, and overlapping, having about 10 scales in the length of 1 mm.; those of the interbrachial spaces are smallest and most closely overlapping. Radial shields small, and slightly swollen, narrow pear-seed shaped, separated their entire length by a narrow wedge-row of scales ; a pair of short, stout scales at their outer ends. Under surface of disk naked. Five short, tapering, blunt arm-spines, evenly spaced on the side arm-plate, and standing at right angles to the arm; the middle spine is stoutest. Large tentacle-pores, but no tentacle-scales. Color in alco- hol, disk gray, arms straw. Station 141, 98 fathoms, 12+ specimens. MUSEUM OF COMPARATIVE ZOOLOGY. at Amphiura concolor sp. nov. Plate XII. Figs. 317-319. Special Marks. —Three mouth-papille on each side, the inner one large and thick, the two outer small and bead-like. Two, sometimes only one, small ten- tacle-scales. Four arm-spines. Radial shields narrow and separated. _ Description of an Individual (Station 195).— Diameter of disk 8mm. Length of arm 65 mm. Width of arm close to disk, without spines, 1 mm. Two very short, small mouth-papille each side of the mouth-angle, and a pair, large, rounded, much swollen at its apex. Four large, thick teeth, with a square cutting edge. Mouth-shield wide spear-head shaped, with a blunt angle within, and the inner sides slightly curved. Side mouth-shields large, broad without, tapering inward, where they just meet. Basal under arm-plates large, pentagonal with the inner angle truncated, broader than long, outer edge straight, lateral sides re-enteringly curved. Side arm-plates rather small, projecting moderately, meeting neither above nor below. Upper arm-plates short and wide, of a trans- verse pointed oval form, with outer and inner edge slightly curved. Disk round and flat, but rather thick, covered with irregular, overlapping scales ; those in the interbrachial spaces being somewhat coarser than the others. Radial shields long and narrow, with outer end rounded, and an acute angle inward, separated their entire length by a single row of scales. Interbrachial spaces on the under surface covered by similar, but finer, scaling. Four short, blunt, rather slender arm-spines, the upper one being slightly shortest. Two small, rounded tentacle-scales, one on the brachial side of the tentacle-pore and one on the side arm-plate. On some pores there is but a single scale. Color in alcohol, straw. Station 195, 1425 fathoms, 2 specimens. Station 191, 800 fathoms, 12+ specimens. Amphiura dalea sp. nov. Plate XII. Figs. 320 - 322. Special Marks. — Four mouth-papillz on a side. Three arm-spines, the middle one swollen. One tentacle-scale. Disk-scales fine, only the central primary plate being conspicuous. First under arm-plate small. Description of an Individual (Station 325).— Diameter of disk 9 mm. Width of arm close to disk, without spines, 1.3mm. Three stout, close-set papillee on either side of the mouth-angle, and two large and much rounded at the apex ; of those on the sides the outermost is largest. Mouth-shields small, triangular, a little longer than wide, rounded on all sides except within, where isa point. Side mouth-shields large, broad without, tapering inward where they just meet. First under arm-plate very small; those beyond are broader than long, angular, and with re-entering curves on the sides where are the ten- tacle-pores ; still farther out they are triangular, with outer edge much curved, 28 BULLETIN OF THE and a truncated angle within. Side arm-plates short, not much projecting, meet- ing above beyond the first upper arm-plate, and below beyond the seventh or eighth. Upper arm-plates slightly swollen, very short and wide, of a trans- verse oval shape, and with a small longitudinal ridge. Disk flat and tolerably thick, covered with thin, small, flat, overlapping scales, with one somewhat larger pounded primary in the centre ; about 4 scales in the length of 1 mm. Radial shields long and broad, bluntly pointed within, nearly or quite sepa- rated their entire length by a narrow wedge of scales. On the interbrachial spaces on the under surface the scaling is much finer than.that above, there being about 15 in the length of 1mm. Three tapering, rather sharp arm- spines, the upper one being shorter than the other two, and the middle one much the stoutest, and swollen. One small longer than broad tentacle-scale on the brachial side of the tentacle-pore; a little way out on the arm there usually is no tentacle-scale. Color in alcohol, pale straw. Station 325, 2,650 fathoms, 5 specimens. Amphiura cernua sp. nov. Plate XII. Figs. 323 -325. Special Marks. —Four mouth-papille on each side. One tentacle-scale. Three arm-spines, the middle one swelled. Disk-scales coarse ; all primary plates conspicuous. First under arm-plate wide and large. Description of an Individual (Station 241).— Diameter of disk 5.7 mm. Length of arm about 24 mm. Width close to disk, without spines .7 mm. Four mouth-papille on each side, of which three are short and blunt (the inner one being more pointed), and two at the apex of the mouth-angle are larger and more swollen. Mouth-shields small, flat, triangular, with a blunt angle inward and outer edge curved. Side mouth-shields broad without, and tapering inward, where they just meet. Under arm-plates large, with a long angle within and slight re-entering curves on tlie lateral sides. Side arm-plates slightly swollen, meeting below some distance out on the arm, and above beyond the first upper arm-plate. Upper arm-plates transverse oval, slightly swollen, with outer and inner edges much curved. Disk flat and slightly angular, covered with thin, semicircular, overlapping scales, the six primary plates being much the largest ; the scaling in the interbrachial spaces is somewhat coarser than on the rest of the disk. Radial shields very large and broad, somewhat longer than wide, of a blunt pear-seed shape ; joined without, separated within by a wedge of two small scales. On the under surface the interbrachial space is covered with very minute scaling. One large tentacle-scale longer than broad. Three short arm-spines, the upper one longest and slender, while the middle one is strongly swollen at its base. Color in alcohol, straw. Station 241, 2,300 fathoms, 1 specimen. é MUSEUM OF COMPARATIVE ZOOLOGY. 29 Amphiura glauca sp. nov. Plate XII. Figs. 326 - 328. Special Marks. — Four mouth-papillz on each side. One tentacle-scale mi- nute and like a lip. Four slender arm-spines. Radial shields long and narrow, and diverging inward. Disk naked below. Description of an Individual (Station 232).—- Diameter of disk 5.5 mm, Width of arm close to disk 1 mm. Four short pointed mouth papille on each side of the mouth-angle, of which that at the apex is much the largest and most rounded. Mouth-shield small, with a rounded angle inward, and outer edge curved. Side mouth-shields small, long triangular, somewhat curved, just _ meeting within. Under arm-plates small, longer than wide, with re-entering curves on the lateral sides, outer corners rounded and a truncated angle within. Side arm-plates small and little projecting, meeting neither above nor below, till some distance out on the arm. Upper arm-plates small, a little broader than long, bounded within by a deep curve, and without by a gentler one, hav- ing a small ridge in the centre, which forms a continuous line along the arm. Disk rather thick, naked below, but covered above with very minute rounded scales, about 7 in the length of 1 mm. where they are finest. Radial shields long and very narrow, tapering inward te a blunt point; they are joined without, and separated within by several small scales. Four slender tapering arm-spines, the upper and under being usually somewhat longer than the two in the middle. One very small lip-like tentacle-scale, on the inner side of the tentacle-pore. Color in alcohol, dull gray. Station 232, 340 fathoms, 4 specimens. Station 236, 420 fathoms, 1 date men. Amphiura Verrilli sp. nov. Plate XII. Figs. 329-331. Special Marks. — Four mouth-papille on each side. Four arm-spines. No tentacle-scales. Radial shields lc rge and wide, and joined for half their length. Description of an Individual (Station 54),— Diameter of disk 6 mm. Width of arm, without spines, close to disk, 1 mm. Four short, blunt mouth-papille on each side, the two at the apex being largest and conical ; between them may be seen the lowest tooth, having a broken edge. Mouth-shields small, rounded, with a slight angle within. Side mouth-shields large, narrow within, where they meet ; broader without, where they curve partially round the mouth-shield. First under arm-plate very small; those beyond are swollen, narrow, longer than broad, having the outer edge much rounded, deep re-entering curves on the lateral sides, and a short, straight side within. Side arm-plates small, separated below, but just meeting above. Upper arm-plates much broader than long, transverse oval, with the inner edge nearly straight, outer edge curved, and blunt angles on the lateral sides. Disk flat, moderately thick and 30 BULLETIN OF THE slightly angular, covered with small, thin, irregular, overlapping scales ; there are six large, widely separated primary plates, one round one in the centre, sur- rounded by five others broader than long. Radial shields large, longer than wide, of an elongated pear-seed shape, their pointed inner ends being separated by two small, angular scales. Interbrachial space on the under surface covered by fine overlapping scales, smaller than those above. Four arm-spines standing close together on the side arm-plates ; they are about as long as an arm-joint, and rather slender and tapering, except the one next the lowest, which is strongly swollen at the base. Large round pores, but no tentacle-scales. Color, gray. Station 54, 2650 fathoms, 1 specimen. Amphiura canescens sp. nov. Plate XII. Figs. 332 - 334. Special Marks. — Five mouth-papille on each side, of which the three mid- dle ones are longest ; point of mouth-angle occupied by the lowest tooth. Two tentacle-scales. Three arm-spines about as long asa joint. Description of an Individual (Station 171). — Diameter of disk 5mm. Arms long and slender. Width of arm, close to disk, without spines, 1mm. Five stout, blunt mouth-papille on either side of the mouth-angle, the three middle ones being longer, broader, and more flattened than the rest. One large, tri- angular papilla, or tooth, at apex of jaw. Mouth-shields broad triangular, with blunt angles and outer edge much rounded. Side mouth-shields long and narrow, but slightly swollen, broader without. than within, where they just meet. First under arm-plate small, pentagonal, with an angle inward and slight re-entering curves on the lateral sides ; the other basal plates are large, with outer edge curved, and wider than the inner, and with lateral sides re- enteringly curved. Side arm-plates not prominent, meeting neither above nor below at the base of the arm. Upper arm-plates broader than long, transverse oval, with lateral ends slightly pointed. Disk flat, but rather thick, its upper surface covered with small, slightly swollen, irregularly shaped, overlapping scales, about 5 in the length of 1 mm. where they are coarsest. Radial shields blunt pear-seed shaped, slightly pointed within, separated by one large and several small scales. Interbrachial spaces on the under surface covered by the same kind of scaling. Three stout, tapering, bluntly pointed arm-spines, about as long as a joint, the lowest slightly longer than the others, placed close to- gether on the side arm-plate. Two tentacle-scales, the one on the ‘brachial side small and narrow, the interbrachial one much larger, with wide, rounded edge. Color in alcohol, nearly white. Station 171, 600 fathoms, 2 specimens. MUSEUM OF COMPARATIVE ZOOLOGY. 31 Amphiura patula sp. nov. »Plate XII. Figs. 335-337. Special Marks. — Five (sometimes only four) mouth-papille on each side. One tentacle-scale. Mouth-papille squarish and crowded. Side mouth-shields large and wide. Disk-scales small, irregular, and crowded. | Description of an Individual (Station 156).— Diameter of disk 14.5 mm. Width of arm close to disk, without spines,2 mm. Five (sometimes only four) squarish, crowded mouth-papille on either side, whereof the outermost and innermost are largest ; besides these there is an odd one at the centre of the apex. Mouth-shields small, rounded triangular, with a blunt angle inward. Side mouth-shields short and stout, rudely triangular in shape, the inner angles not quite meeting at the apex of the mouth-shield. Under arm-plates pentag- onal, with inner angle sometimes truncated, outer edge slightly rounded, and small re-entering curves on the lateral sides. Side arm-plates narrow, bent, not very prominent, meeting above, but just separated below. Upper arm-plates much broader than long, transverse oval, with outer and inner edges gently eurved. Disk flat, covered with thin, flat, irregular, crowded scales, among which six small widely separated primary plates are with difficulty distinguish- able. Radial shields large and broad, of a wide pear-seed shape, separated their entire length by a narrow wedge of three or four scales. On the under surface the scales are much finer and more rounded. Three short, round, bluntly tapering arm-spines, the middle one larger than the others but not so Jong as an arm-joint, and all placed low on the side arm-plate. Only one longer than wide, somewhat swollen tentacle-scale, on the brachial side of the tentacle-pore. Except that it has usually five, instead of four, mouth-papille on a side, this Species stands related to A. dalea, from which it is distinguished by smaller arm-spines, different under arm-plates, and coarser, more irregular scaling, Color in alcohol, grayish. Station 156, 1975 fathoms, 4 specimens. Note. — The following are species previously known and now brought back by the ‘‘ Challenger,” namely, A. sguamata, A capensis, A Otteri, A. duplicata, A. Studer (A. antarctica), A. depressa. Amphiura capensis Ln. Amphiura capensis. Of. Kong. Akad. Oph. Viv., 1866, p. 320. Station 141, Lee’s Point, Cape Town, 98 fathoms, 12-++ specimens. Amphiura duplicata Lym. / Amphiura duplicata, Tl. Catal., No. VIII., Pt. 2, p. 19. Station 56, 1,075 fathoms, 4 specimens. Quite common in less depths throughout the West Indies. A. duplicata is Sa BULLETIN OF THE somewhat variable ; and, especially, the first under arm-plate is not always broken in two. Numerous specimens from the second “ Blake” Expedition show usually only three arm-spines; three and often four irregular mouth- papille on each side, and disk-scales varying in thickness. Amphiura squamata Sars. Amphiura squamata. , Middelhav. Lit. Fauna, II., 1857, p. 84. Station 141, 98 fathoms. Station 163, 120 fathoms, 1 specimen. Such diverse localities further prove the cosmopolite nature of this species. Amphiura Otteri? Lsn. Amphiura Ottert ? Of. Kong. Akad. Dr. Goés, Oph., 1871, p. 631. Station 76, 900 fathoms, 2 specimens. Station 45, 1,240 fathoms, 2 speci- mens. Station 78, 1,000 fathoms, 1 specimen. Station 50, 1,250 fathoms, 1 specimen. I have not much question that this is Ljungman’s A. Olteri which has some variety as to size and curve of spines. The unique originals of this and many other species were, with great kindness, lent me by Prof. Lovén; and Dr. G. O. Sars showed a similar generosity. Amphiura depressa ? Amphipholis depressa Ljn. Of. Kong, Akad. Oph. Viv., 1866, p. 312. Station 233, 15 fathoms, 1 specimen. Amphiura Studeri. Amphiura antaretica Studer. Monatsb. Kon. Akad. Wissen., Berlin, 1876, p. 461. Station 151, off Herd Isl., 75 fathoms, 1 specimen; var. Off Marion Isl, 50 -'75 fathoms, 10 specimens. Station 145, off Prince Edward’s Isl., 310 fath- oms, 1 specimen (young). Off Prince Edward’s Isl., 85 — 150 fathoms, 1 speci- men. Royal Sound, Kerguelen Isl., 28 fathoms, 12+ specimens. Balfour Bay, Kerguelen Isl., 20 - 60 fathoms, 8 specimens. As I have combined Amphipholis with Amphiura, Prof. Studer’s name has become a duplicate to (Amphipholis) antarctica Lin. I take, therefore, the liberty of giving it the name of its discoverer, who kindly identified these specimens by his own. Ophiocnida pilosa sp. nov. Plate XII. Figs. 341-343. Special Marks. — Disk scaling hidden. Disk set with stout simple spines. Five tapering arm-spines, the lowest one longest. A slender mouth-papilla on each side, and a pair of thick ones at apex of mouth-angle. MUSEUM OF COMPARATIVE ZOOLOGY. 30 Description of an Individual (Station 162).— Diameter of disk 5.2 mm. Arm broken, but apparently eight or ten times the diameter of disk. Width of arm near disk 1.2mm. The short narrow mouth-angle has at its base on either side a spiniform papilla, and at its apex a pair, stouter and more angular. Mouth- shields longer than broad, nearly oval. Side mouth-shields triangular, some- what curved round the mouth-shield, not meeting within. Under arm-plates narrow, longer than broad, with eight sides, but having the angles rounded and nearly obliterated ; lateral sides re-enteringly curved. Side arm-plates feeble, nearly or quite meeting above, but not below. Upper arm-plates nearly twice as wide as long, of a transverse oval shape, with inner curve deeper than outer. Disk delicate but rather thick, sparsely set above and below with small spines ; in the centre may be seen some round, very thin, primary plates ; the rest seems naked, but on drying a very fine, delicate scaling appears. Radial shields much longer than broad, slightly curved, meeting without, widely separated within ; length to breadth 1:.5. Five cylindrical, tapering, blunt arm-spines, the lowest somewhat the longest ; lengths to that of an under arm-plate, .5, .5, .5, .5, .7:.5. No tentacle-scales. Color in alcohol, pale gray. Station 162, 38 fathoms, 2 specimens. Station 212, 10-20 fathoms, 1 speci- men. Ophiocnida scabra sp. nov. Plate XII. Figs. 344-346. Special Marks. — Disk much puffed. Radial shields long and narrow. Five or six short stout arm-spines, the second longest. Two minute mouth-papill on either side, and a pair of larger ones at apex of mouth-angle. Description of an Individual (Station 128).— Diameter of disk 6mm. Length of arm about 40 mm. Width of arm near disk 1.3 mm. Two minute, bead- like papillz on each side of base of small mouth-angle, and a pair, much larger, at its apex. Mouth-shields small, rounded, about as broad as long. Side mouth-shields small, bent, wider without than within, where they do not meet. Under arm-plates as broad as long, bounded by a curve without, and within by three sides of an octahedron. Side arm-plates narrow, widely separated above and below, and having a feeble spine-ridge. Upper arm-plates two and a half times as broad as long, of a clean, transverse oval shape. Disk extremely puffed in the interbrachial spaces by the swollen ovaries. This swollen portion, both above and below, is naked, and sparsely set with minute, peg-like spines ; but above the surface is finely and pretty uniformly scaled, with about 6 scales in the length of 1 mm. Radial shields long and very narrow, slightly bent towards each other, nearly or quite separated their whole length by a narrow strip of two scales ; length to breadth 1.5 :.3. Six short, thick, microscopically thorny arm-spines, whereof the two uppermost are longest, somewhat flattened, pointed, and have a minute beak ; those below diminish constantly in length, and are almost club-shaped ; lengths to that of a lower arm-plate, .5, .7, .4, .3, 3, .2 : .3. One round tentacle-scale. Tentacles papillose, as in Ophiothriz. Color in alcohol, pale yellowish-brown, mottled and speckled with darker. VOL. VI. — NO. 2 8 34 BULLETIN OF THE Station 128, off Bahia, Brazil, 1,275 fathoms, 1 specimen. This eccentric species might almost as well go with Ophiactis. AMPHILEPIS Lyn. Amphilepis patens sp. nov. Plate XII. Figs. 338-340. Special Marks. — Disk flat, round and smooth. Mouth-angle large with three wide mouth-papille on each side. Second pair of mouth-tentacles en- circled by hard parts of the mouth. Description of an Individual.— Diameter of disk, 11 mm. Width of arm near disk, 2mm. Mouth-papillz broad and irregular ; on either side of the large prominent mouth-angle, at the onter corner, are two more or less closely joined ; and, at the apex, a larger pair which, through the gap between them, show the small lowest: tooth. Mouth-shields rather small, rounded, broader than long, often with a little peak inward ; length to breadth, 1:1.2. Side mouth-shields short and wide; narrower within, where they barely meet. Under arm-plates, rather small, as broad as long, shield-shaped, with a gently curved outer side, lateral sides a little re-enteringly curved, and an obtuse angle within. Side arm-plates wide, with a knob-like spine-crest, meeting fully above and nearly or quite below. Upper arm-plates transverse oval, twice as wide as long, separated by the side arm-plates. Disk round and flat, but not thin ; covered above and below with rounded, overlapping, flat, rather large, very thin, translucent scales, with indistinct outlines ; above they are of pretty even size, except a marginal row of larger, each of which is .7 mm. long ; below they are much finer; about 3in the length of 1 mm. Radial shields large, of a rhomboidal form, except that the outer side is rectangular, much longer than wide, strongly diverging, with the outer ends nearly touching, but separated within by a broad wedge of numerous scales ; length to breadth, 3:1.2. Three stout, short, cylindrical, tapering, blunt arm-spines ; lengths to that of an under arm-plate, 1.1, 1.2, 1.3 : .8. Tentacle-pores large, with one minute scale on lateral side of under arm-plate. The roots of the second pair of mouth-tentacles come low down, and thus seem framed by the surrounding hard parts. Color in alcohol, pale gray. Station 299, 2,160 fathoms, 1 specimen. Amphilepis papyracea sp. nov. Plate XVI. Figs. 429-431. Special Marks. — Disk thin and flat, with thin, fine scales. Three tapering, rather slender arm-spines, a little longer than an arm-joint. No tentacle-scale. Radial shields nearly or quite separated their entire length. Description of an Individual (Station 198).— Diameter of disk 9 mm. MUSEUM OF COMPARATIVE ZOOLOGY. 35 Width of arm close to disk, without spines, 1.5 mm. Two wide, slender pointed mouth-papille on each side, standing high up on the jaws. Four teeth, the three upper ones flat and wide, with a curved cutting edge ; the lowest thicker and more conical. Mouth-shields flat and small, of a wide heart-shape with a rounded angle inward and outer edge rounded ; length to breadth .7: 1. Side mouth-shields wide without, where they enclose the corner of the mouth-shield, narrow and just meeting within. Under arm- plates pentagonal with inner angle slightly truncated, lateral sides re-enteringly curved, and outer edge straight. Side arm-plates with outer edge swollen ; meeting above, and nearly so below. Upper arm-plates thin and translucent, of a transverse oval shape, about twice as wide as long. Disk smooth, flat, angular and very thin, covered with small, thin, rounded, ill-defined scales, Radial shields with a vague outline, of a bent pear-seed shape, nearly touching without, separated within by an oval of five scales ; length to breadth 2.5: 1. Scaling on lower interbrachial space finer than that above. Three rather slender, bluntly pointed, tapering, cylindrical arm-spines, a little longer than an arm- joint, well up on the outer edge of side arm-plates. Tentacle-pores large, but without a scale. Color in alcohol, pale gray. Station 198, 2,150 fathoms, 1 specimen. Amphilepis tenuis sp. nov. Plate XVI. Figs. 432 -434. Special Marks. —QOne minute tentacle-scale. One mouth-papilla on each side.* Radial shields short and wide, and joined for half their length. Description of an Individual (Station 237).— Diameter of disk 4 mm. Width of arm close to disk, without spines, .7 mm. One wide, pointed, some- what bent mouth-papilla high up on each side the mouth-angle, and a ‘pair, short, thick, and rounded, at the apex. Mouth-shields small, twice as broad as long, of a transverse diamond-shape, with rounded angles. Side mouth-shields three-sided, short and swollen, wider without, tapering rapidly within, where they scarcely meet. Under arm-plates broad pentagonal, with a short angle within, outer side nearly straight, and laterals slightly curved. The first plate is large and of a truncated wedge-form. Side arm-plates meeting broadly above and nearly touching below. Upper arm-plates twice as broad as long, of a nearly semicircular outline, with the curve inward. Disk flat and angular, covered with very thin scales; in centre of the disk is a rosette of six large ill- defined primary plates, each nearly surrounded by minute scales. Radial shields short, wide pear-seed shaped, joined for the outer half of their length, narrowly separated within by a wedge of small scales. Scaling on interbra- chial space below, much finer than that above. Three short, cylindrical, bluntly pointed arm-spines. One minute, rounded tentacle-scale, which easily falls off. Color in alcohol, faint greenish-gray. Station 237, 1,875 fathoms, 1 specimen. * Sometimes broken in two, as in the figure. 36 BULLETIN OF THE Amphilepis norvegica? Lun. Amphilepis norvegica. Of. Kong. Akad. Oph. Viv., 1866, p. 322. Station 45, 1240 fathoms, 1 specimen. Station 46, 1350 fathoms, 3 specimens, So far as one may judge, without having a proper series, these are the adult of Ljungman’s original. They have the disk as largeas9mm. ‘The radial shields are pretty large and separated, and there is no tentacle-scale. : OPHIACTIS. TABLE OF SPECIES HEREIN DESCRIBED. Nore. — Following these descriptions will be found the species previously known and brought back by the “‘ Challenger,” namely, O. asperula, O carnea, O. Savignyi, and O Miilleri. Skin thick and much obscuring the scaling and mouth-shields. Radial shields narrow and small, Five short, thick, blunt, flattened arm-spines. } © resiliens. Disk-scales distinct and naked, without’ spines. Three stout, blunt, tapering, cylin- drical arm-spines. One large, flat mouth-papilla on each side. Teeth lobed. viel arms. Disk-scaling coarse, and with few or no spines. Three or four stout, blunt, tapering arm-spines. Two or three mouth-papillz on each side. Teeth lobed. Disk-secales coarse, and set with numerous short spines. Radial shields short and } triangular. Four stout, cylindrical, tapering arm-spines. One mouth-papilla on each - O. nama, side. Five arms. j Disk finely scaled, and set with short, minute spines. Radial shields small and pear- seed shaped. Four moderately stout, tapering arm-spines, the uppermost longest.} O. hirta. Two or three minute mouth-papillz on each side. Seven arms. Disk-scales coarse and thick, with large radial shields. No spines, except a few near the margin. Four rather long and slender arm-spines, the upper one longest Two} O. poa- mouth-papillze on each side. Disk-scales larger in centre, where primary plates may be distinguished in a rosette. No spines, or only an occasional minute one on the margin. Three or four rather long} O canotia. and tapering arm-spines. Two mouth-papillze on each side. O flexuosa. O. cuspidata, Of the above seven species, the first belongs with the shallow-water type of O. Savignyt; the rest come under the type of O. Baili, whose species often inhabit the deep sea. Ophiactis resiliens sp. nov. Plate XIII. Figs. 362 - 364. Special Marks. — Skin thick and much obscuring the scaling and mouth- shields. Radial shields narrow and small. Five short, thick, blunt, flattened arm-spines. Description of an Individual (Port Jackson). — Diameter of disk 6.5 mm. Length of arm 38 mm. Width of arm near disk 1.5mm. Mouth-angle very small and short, carrying on either side two small, flat, squarish papille, and, at its apex, a third, rounded, with a minute point like the teeth. Mouth-shields small, of a transverse oval shape ; length to breadth .7: .5. Side mouth-shields rather small and curved, broader without than within, where they meet. Under arm-plates small and rounded, about as long as broad, having outer side curved and inner side with ill-marked angles. Side arm-plates projecting in a strong spine-ridge. Upper arm-plates flat, transverse oval in form, about twice as broad as long. Disk covered below by a thick, naked skin, and above by MUSEUM OF COMPARATIVE ZOOLOGY. 37 fine, crowded, irregular, thin scales, of the smallest of which there are about 5 in the length of 1 mm. Those near the radial shields are much larger ; and there may be also obscurely distinguished six round primary plates, widely separated by the fine scaling. The disk margin is beset with minute, sharp, peg-like spines. Radial shields long and narrow, touching without, separated within by a narrow wedge of about three scales; length to breadth 1.3: .4. Five short, thick, blunt, flattened arm-spines, of which the uppermost is the stoutest, but not longer than the rest. One oval tentacle-scale. Color in alco- hol, above, olive green, mottled and banded with lighter ; below, yellowish brown, with under arm-plates and arm-spines marked with orange. Port Jackson, Australia, 30-35 fathoms, 1 specimen. Ophiactis flexuosa sp. nov. Plate XIII. Figs. 347-349. Special Marks. — Disk-scales distinct and naked, without spines. Three stout, blunt, tapering, cylindrical arm-spines. One large flat mouth-papilla on each side. Teeth lobed. Five arms. Description of an Individual (Station 171).— Diameter of disk 7mm. Length of arm about 35mm. Width of arm near disk 2.3mm. Each side of the short, narrow mouth-angle is occupied by a single very large, wide, flat: papilla, while a third, standing under and resembling the teeth, is at the apex, and has a rounded figure, with a decided peak or little lobe within. Mouth-shield somewhat broader than long, of a rounded diamond-shape. Side mouth-shields rather broad, wider without than within where they meet. First under arm- plate small, and wider within than without; those beyond are narrow com- pared with the width of the arm, much rounded, ofa short transverse oval shape, with the inner side somewhat angular. Side arm-plates very wide, meeting neither above nor below, and having but a feeble lateral projection. Upper arm-plates broad and short, two and a half times as wide as long, of an elongated transverse diamond-form, sometimes with outer side so straight as nearly to be triangular. Disk without spines, and covered above with coarse, rounded, thick, overlapping scales, of which there are four or five radiating rows in the narrowest part of each interbrachial space. Below, the scales of the in- terbrachial space are much finer (4 or 5 in the length of 1 mm.), and regularly imbricated. Three short, stout, cylindrical, scarcely tapering arm-spines of nearly equal length, and about as long as one anda half joints; the upper spine stoutest. One large oval tentacle-scale. Color in alcohol, pale brown. Station 171, 600 fathoms, 2 specimens. Station 142, 150 fathoms, 10 speci- mens, young ? The ten specimens from Station 142, 150 fathoms, may be the young of this species. They have six arms, while O. flexuosa has but five, and are scarcely to be distinguished from O. plana; and the question arises whether O. plana be not a young animal. The so-called adult of O. Miilleri has five arms, and the young six. F 38 “BULLETIN OF THE . Ophiactis cuspidata sp. nov. Plate XIII. Figs. 359-361. Special Marks. — Disk-scaling coarse, and with few or no spines. Three or four stout, blunt, tapering arm-spines. Two or three mouth-papille on each side. Teeth lobed. Description of an Individual (Station 170).— Diameter of disk 5mm. Length of arm 25mm. Width of arm close to disk 1.3mm. ‘Two large, broad, flat mouth-papillz on each side, whereof the outer one is larger. Seven or eight large flat teeth, of a very wide heart-shape, and having a little lobe, or peak, within. Mouth-shields broader than long, wide heart-shape, or transverse diamond-shape, with rounded angles ; length to breadth .6:.8. Side mouth- shields stout, slightly curved, rather broad, meeting within, where they have a rounded end. First under arm-plate stout and rather large, wider within than without, and having re-enteringly curved lateral sides. The plates beyond are shield-shaped, widest without, and having a somewhat obtuse angle within. Outer side curved, lateral sides re-enteringly curved. Side arm-plates stout, nearly meeting above and below, and having a well-marked spine-crest. Upper arm-plates broader than long, of a wide, transverse diamond-shape, with the outer angle much rounded. Disk thick and covered above with large, rather swollen scales, whereof there are three lines in each interbrachial space ; in the centre are six large, somewhat angular, primary plates, separated by single lines of much smaller angular scales ; the lower interbrachial space is covered with fine, thickened scales, from 5 to 8 in the length of 1mm. Radial shields blunt pear- seed shape, swollen; nearly or quite separated by a wide wedge of two or three scales. Along margin of disk are a few small, peg-like spines. Four stout, smooth, tapering, regular arm-spines, the upper one longest ; lengths to that of a lower arm-plate 1.7, 1.1, 1, .7 : .6. One stout, nearly oval tentacle-scale. Color in alcohol, pale gray. Station 170, 520 fathoms, 5 specimens. Station 171, 600 fathoms, 1 speci- men. Ophiactis nama sp. nov. Plate XIII. Figs. 350-352. Special Marks. — Disk-scales coarse, and set with numerous short spines. Radial shields short and triangular. Four stout, cylindrical, tapering arm- spines. One mouth-papilla on each side. Five arms. Description of an Individual (Station 174). — Diameter of disk 6mm. Length of arm about 45 mm. Width of arm near disk 2.2mm. One large, wide, flat mouth-papilia at base of mouth-angle on each side, and one (which may be called the lowest tooth) at the apex ; this last is broad and rounded, with a minute peak within. Mouth-shields of a much rounded, transverse diamond- shape; length to breadth 8: 1.1. Side mouth-shields stout, nearly meeting MUSEUM OF COMPARATIVE ZOOLOGY. 39 without, broader without than within, where they touch. First under arm- plate small and three-sided, wider within than without : those beyond are one half broader than long, with a curved outer side, and an irregular, more or less truncated angle within. Side arm-plates unusually wide, but not much pro- jecting, nearly meeting above and below. Upper arm-plates much wider than long, three-sided, with a faintly curved outer side, and an angle, sometimes trun- cated, within. Disk plentifully set with short, slender, cylindrical spines, and ‘covered with well-rounded overlapping scales, which are large above (2 or 3 in the length of 1 mm.), and more regular and much smaller below (4 or 5 in 1 mm.). Radial shields sunken, rudely triangular, short and wide, separated by a broad wedge of three or four large scales; length to breadth 1.2:1. Four cylindrical, tapering, blunt, rather stout arm-spines, the two upper ones largest and somewhat longer than an arm-joint. One large, oval tentacle-scale. Color in alcohol, pale straw. Station 174, 210-610 fathoms, 1 specimen. Station 171, 600 fathoms, 1 specimen. Ophiactis hirta sp. nov. Plate XIII. Figs. 365-367. Special Marks. — Disk finely scaled, and set with short, minute spines. Radial shields small and pear-seed shaped. Four moderately stout tapering arm-spines, the uppermost longest. Two or three minute mouth-papille on each side. Seven arms. Description of an Individual (Station 164%).— Diameter of disk 4.3 mm. Length of arm about 14 mm. Width of arm near disk 1.2mm. Two or three small, narrow, scale-like mouth-papille on either side of the very nar- row mouth-angle ; and one, wide, flat, and pointed, at the apex ; this last may, as in all similar cases, be considered the lowest tooth. Mouth-shields small, of a much rounded diamond-shape ; sometimes nearly circular. Side mouth-shields narrow, of nearly equal width, meeting within. Under arm-plates rather small, as broad as long, bounded without by a strong curve, and within by three sides of an octagon. Side arm-plates stout, projecting laterally in a well marked spine-ridge, meeting neither above nor below. Upper arm-plates a little broader than long, transverse oval, with the inner sides more or less angular. Disk covered with coarse, thickened, irregular scales, those of the under surface being sometimes wholly obscured by a thick skin ; those in the centre are largest, but the primary plates are not readily distinguishable ; there are small, peg-like spines scattered over the entire surface. There are seven pairs of radial shields, which are small, sunken below the disk-surface, of a blunt pear-seed shape, and separated by a rather wide wedge of three scales. Four smooth, rounded, tapering, moderately stout arm-spines ; the upper one longest; lengths to that of an under arm-plate, 1,.8, .7,.7:.5. One stout, oval _tentacle-scale. Color in alcohol, gray mottled with pale brown. Station 164%, 400 fathoms, 1 specimen. 40 BULLETIN OF THE Ophiactis poa sp. nov. Plate XIII. Figs. 356-358. Special Marks. — Disk-scales coarse and thick, with large radial shields; no spines except a few near the margin. Four rather long and slender arm-spines, the upper one longest. 'Two mouth-papille on each side. Description of an Individual (off Tristan d’Acunha).— Diameter of disk 5mm. Length of arm about 30mm. Width of arm near disk 1mm. On each side of the short narrow mouth-angle are two rather large, squarish, flat papille, of which the outer one is broader ; at the apex is usually a very small heart-shaped papilla, similar in shape to the larger teeth above it. ‘Mouth- shields much wider than long, of a rounded transverse heart-shape ; the inner sides a little re-enteringly curved. Side mouth-shields of nearly equal width, meeting broadly within. Under arm-plates wide shield-shaped, bounded without by a broad curve, within by an obtuse or truncated angle, and on the lateral sides by re-entering curves. Side arm-plates nearly meeting above and below, not very wide, but projecting in a well-marked spine-crest. Upper arm-plates broader than long, fan-shaped with an obtuse angle inward. Disk covered with coarse, overlapping scales ; those below regular and smaller, about 4 in the length of 1 mm.; those above much larger and more irregular; in the centre an irregular rosette of large, rounded plates, and in each interbrachial space about three radiating rows of elongated scales. The disk margin is sparsely set with small peg-like spines, Radial shields large, of an angular pear- seed shape, separated wholly by a narrow wedge of two or three scales ; length to breadth 1.5: 1. Four slender, cylindrical tapering arm-spines, the upper- most longest ; lengths to that of an under arm-plate 1.2, .8, .8, .8 : .5. One large, oval tentacle-scale. Color in alcohol, pale gray. Off Tristan d’Acunha, 1,000 fathoms, 2 specimens. Off Tristan d’Acunha, 500 fathoms, 10 specimens. Both Station 135. Ophiactis canotia sp. nov. Plate XIII. Figs. 353-355. Special Marks. — Disk-scales larger in centre, where primary plates may be distinguished in a rosette ; no spines, or only an occasional minute one on the margin. Three or four rather long and tapering arm-spines. Two mouth-pa- pille on each side. Description of an Individual (Station 73).— Diameter of disk 5.5 mm. Length of arm about 17mm. Width of arm near disk 1.8mm. Two flat, rather large, squarish mouth-papille on each side of the narrow mouth-angle, and one at the apex, similar in form to the teeth, which are broad heart-shape with a peak within. Mouth-shields wider than long, broad heart-shaped with a rounded angle within, or wide transverse, rounded diamond-shaped. Side mouth-shields rather narrow, of about equal width, meeting fully within. First under arm-plate small and wider within than without ; those beyond are wide shield-shaped, bounded without by a curve, on the lateral sides by re-entering MUSEUM OF COMPARATIVE ZOOLOGY. 41 curves, and within by an obtuse or truncated angle. Side mouth-shields of moderate width, nearly meeting above and below, and having a well-marked spine-crest. Upperarm-plates broad, transverse diamond-shaped, with outer and inner angles rounded. Disk covered with rather thick overlapping scales, which are finest below, near the mouth-shields, where there are about 7 in the length of 1 mm. Above, the centre is occupied by a rosette of two circles of large rounded plates partially separated by a few small scales. Radial shields ‘short, wide pear-seed shaped, separated their entire length by a narrow wedge of three scales. On interbrachial spaces below, a few minute, peg-like spines. Four short, cylindrical, tapering, blunt arm-spines, all stout, especially the lower ones ; upper spine longest, and about as long as one and a half joints, One large oval tentacle-scale. Color in alcohol, pale straw. Station 73, 1,000 fathoms, 2 specimens. Ophiactis asperula Lrx. Ophiactis asperula. Addit. ad Hist. Oph., Pt. II., 1859, p. 130. Ophiactis magellanica Ljn. Of. Kong. Akad. Oph. Viv., 1866, p. 325. Station 308, 175 fathoms, 1 specimen. Station 311, 245 fathoms, 1 specimen. Station 312, 10-15 fathoms, 12+ specimens. Station 315, 5-12 fathoms, 7 specimens. Ophiactis carnea Lun. Ophiactis carnea. Of. Kong. Akad. Oph. Viv., 1866, p- 324. Station, Simon’s Bay, Cape of Good Hope, 10-20 fathoms, 4 specimens. Ophiactis Savignyi Ln. Ophiactis Savignyi. Of. Kong. Akad. Oph. Viv., 1866, p. 323. Station 208, 18 fathoms, 1 specimen. Zanzibar, 10 fathoms, 2 specimens. Ophiactis Miilleri Lrx. Ophiactis Miilleri. Vid. Meddel., Jan. 1856, p. 12. Off Bahia, Brazil, 7-20 fathoms, 2 specimens, var. quinqueradia. Station 122, 350 fathoms, 2 specimens. OPHIOSTIGMA Lrx. Ophiostigma africanum. Plate XIII. Figs. 368-370. Special Marks.— Arms more than eight times the diameter of disk. Outer mouth-papille very wide. Radial shields long, narrow, and joined. Description of an Individual (Cape de Verde Isl.). -— Diameter of disk 2.2 mm. 42 BULLETIN OF THE Length of arm 18 mm, Width of arm near disk.6mm. Three mouth- papilla on each side of a mouth-angle, whereof the two inner ones are small, short, and almost conical, while the outer is straight and very wide, extending from the first under arm-plate about two thirds the length of an angle. Mouth- shields three-sided, with rounded angles, bounded without by a curve, and within by a rounded angle ; length to breadth, .2: .8. Side mouth-shields wide, a little broader without than within, where they fully meet. Under arm-plates small, pentagonal, with outer side nearly straight, lateral sides a little re-enteringly curved, and an angle within. Side arm-plates nearly meet- ing above and below, and having a thick, low, spine-crest. Upper arm-plates small, irregular transverse oval, with the inner curve deeper than the outer. Disk rather thick, standing nearly clear of the arms, as is usual in the genus : covered with fine, thin, nearly equal, indistinct scales, whereof most are rounded, but some, near the centre, are angular: there are about 12 in the length of 1mm. where they are finest. Along margin of disk are minute, peg-like, scattered spines, which are not: jointed at the base. Radial shields long, nar- row, and closely joined ; length to breadth, .6: .2. At their outer ends are visible the points of the genital plates, in two little lobes. Three stout, equal, peg-like, very short arm-spines, standing nearly at right angles with the arm. Two minute, longer than broad tentacle-scales standing diagonally with the arm-plate. Color in alcohol, nearly white. St. Vincent, Cape de Verde Islands, 7 specimens. O. africanum differs from O. isacanthum in having longer arms, and longer, narrower radial shields ; and from O. formosa by its wide outer mouth-papilla and longer arms. OPHIOPHOLIS Mixt & TRoscu. Ophiopholis japonica sp. nov. Plate XIII. Figs. 374-36. Special Marks. — Upper disk covered with thin scales and large radial shields, neither of which have grains or spines, except the marginal scales. Five stout, cylindrical, tapering arm-spines. Description of an Individual (Station 236).— Diameter of disk 10 mm. Length of arm about 40mm. Width of arm without spines near disk 2.7 mm. Three or four small, irregular, flat, scale-like mouth-papille on each side, and a flat clump of short, bead-like tooth-papillee at apex of mouth-angle. Mouth- shields and side mouth-shields somewhat obscured by thick skin. The former are transverse oval, much wider than long ; length to breadth .8:1.3. Side mouth-shields small and short, with rounded ends, rather wider within than without, and somewhat bent. Under arm-plates a little wider than long, slightly separated, and with rounded corners. Side arm-plates closely soldered with their neighbors, meeting neither above nor below, rising laterally MUSEUM OF COMPARATIVE ZOOLOGY. 43 in astrong spine-ridge. Upper arm-plates transverse oval, twice as broad as long, slightly swollen, each surrounded by a single line of rounded granules, which are broader than long. Disk round and thick, with a flat top, covered with thin, variously shaped scales, which, near the margin, are obscured by thick skin; those of the centre small, round, and arranged in a rosette ; those farther out, larger and elongated, arranged in three or four rows between the radial shields in the interbrachial spaces, where they are beset with a few scattered - grains, which at the margin become much more numerous and larger, and appear as very short spines. Interbrachial spaces below covered with a few grain-like spines. Radial shields large, pear-seed shaped, much longer than wide, separated usually by a line of two large and two smiall scales. Genital openings large and extending about two thirds the distance to the margin, Five, rarely six, stout cylindrical, blunt, tapering arm-spines, whereof the second and third are stoutest, and as long as one and a half arm-joints. One, and on the first two joints sometimes two, small, rounded tentacle-scales. At tip of arm are four slender spines, of which the lowest takes the form of a flat, long, three-toothed hook, as elsewhere in this genus. Color in alcohol, above, light pink ; below, pale straw. Prof. P. Martin Duncan has recently published (Linnean Soc. Journ. Zool., XIV. 460, 479) an Ophiuran, Ophiolepis mirabilis, of which he re- marks: “This common species has the disk of Ophiolepis as diagnosed by Miiller and Troschel, that is to say, the scales, which are of good size, and the large radial shields, are environed by rows of small scales as by belts. But the upper arm-plates have also the supplementary rows of small scales around them, and there are also large accessory side pieces. Moreover, there are hooks on the side arm-plates. This mixture of Ophiolepian and Ophiopholian characters is very interesting ; and this species, I consider, renders the abolition of Ophio- pholis as a genus inevitable.” The meaning of this passage is not quite clear, because Miiller and Troschel (Syst. d. Asterid., p. 89) diagnosed, not the whole genus, but only the first sec- tion of it, as having belts of scales round the disk plates (e. g. 0. cincta). To this section Ophiolepis has been restricted. The third section they described as having spines on the scales. This last is Ophiopholis, a genus now rec- ognized as quite remote from the true Ophiolepis, which stands nearer Ophio- glypha, Pectinura, &c., while Ophiopholis approaches the Amphiure through Ophiactis asperula. It is evident that Ophiolepis mirabilis is a true Ophiopholis, lacking none of its characters, and standing quite near the typical O. aculeata. The fact that certain small scales surround larger ones is not here of generic importance, and probably results from the young stage of the specimen, which, to judge from the figures, had a disk not exceeding 4 mm. in diameter. Ophio- phos japonica differs from the old species as well as from O. mirabilis in its more slender arm-spines, and in having the radial shields and much of the upper disk free of grains or spines. Station 235, 565 fathoms, 1 specimen. Station 236, 420-775 fathoms, 3 specimens, 44 BULLETIN OF THE OPHIOCHONDRUS Lym. Ophiochondrus stelliger. Plate XIII. Figs. 371-3173. Special Marks. — Disk finely and evenly granulated on both sides. Four slender arm-spines, whereof the uppermost is much the longest. Description of an Individual (Station 320), — Diameter of disk5mm. Length of arm16mm. Width of arm near disk 1.3mm. Three mouth-papille on each side, whereof the two outer are flattened and squarish, while the inner- most is stout, rounded, tapering, and peg-like. Apex of mouth-angle occupied by the lowest tooth, which sometimes is represented by two blunt, spiniform papille similar to their next neighbor. Four rather narrow teeth, which sometimes are almost spiniform, but usually are flattened. Mouth-shields much wider than long, with a well-marked obtuse angle inward and the outer side gently curved ; length to breadth,.7 : 1.1. Side mouth-shields long, rather narrow, of nearly equal width, slightly curved, and fully meeting within. First under arm-plate small, longer than broad, hexagonal, with rounded corners ; the plates beyond are rather small, wider than long, bounded without by a broad curve, and within by an obtuse angle ; the lateral sides are very short, or are confounded in the outer curve. Side arm-plates small, somewhat wider than long, fan-shaped, with inner angle rounded. Disk rather thick, finely and uniformly granulated above and below, about 17 grains in the length of 1 mm. Four cylindrical, tapering, rather slender arm-spines, whereof the uppermost is longest : lengths to that of an arm-joint, 1.1, .6, .5,.4: .6. One small, narrow tentacle-scale. Color in alcohol, straw. Station 320, 600 fathoms, 7 specimens. OPHIOCONIS Lrx. Ophioconis antarctica sp. nov. Plate XIV. Figs. 380-382. Special Marks. — Seven slender, cylindrical, tapering arm-spines, the two upper ones longest. One large tentacle-scale. Disk closely granulated, except mouth-shield ; 5 or 6 grains in the length of 1 mm. Description of an Individual (Station 150).— Diameter of disk 13 mm. Length of arm about 60 mm. Width of arm at base, without spines, 2 mm. There are to each angle of the mouth twelve or fourteen papille, of which the innermost are slender and pointed, while the outer one on either side is broad and squarish ; at the apex there is a cluster of four or five, which properly might be called tooth-papille. Five or six rather narrow, flat, blunt teeth, whereof the lowest is often split in two. Mouth-shields broad triangular, with a blunt angle inward and outer edge nearly straight ; they are more or less obscured by granules, which completely hide the side mouth-shields. These MUSEUM OF COMPARATIVE ZOOLOGY. 45 are small, longer than wide, and broader without than within, where they nearly or quite meet. Under arm-plates much broader than long, pentagonal, with a blunt inner angle, outer edge slightly curved, and laterals re-enteringly curved. Side arm-plates somewhat projecting, nearly meeting below, but well separated above by the thick, broad, somewhat arched upper arm-plates, which are wide fan-shaped, with a blunt angle inward. Under the microscope they appear minutely tuberculous, while the lower plates are ornamented with wavy ‘lines. Disk thick and nearly round, completely covered with coarse, rounded granules, 5 or 6in the length of 1 mm. on the upper surface, and more scattered below. The underlying scales are extremely thin and smooth. Genital open- ings long, extending from outer corners of mouth-shield nearly or quite to the margin of disk. Seven long, smooth, cylindrical, tapering arm-spines, the two upper ones as long as three or four arm-joints ; the others somewhat shorter. One long, wide tentacle-scale, with a rounded point occupying the lateral side of the under arm-plate. Color in alcohol, nearly white. Station 150, 150 fathoms, 12-+- specimens. Off Prince Edward Isl., 85-150 fathoms, 12+; specimens. Off Marion Isl., 50-75 fathoms, 12-+ specimens. Ophioconis pulverulenta sp. nov. Special Marks. — Disk finely, closely, and evenly granulated, with about 14 grains in the length of 1mm. Eight or nine Jong, delicate, somewhat flattened arm-spines, the three uppermost longest, and nearly equal. Two tentacle- scales. | Description of an Individual (Station 172).— Diameter of disk 12 mm. Length of arm about 55mm. Width of arm close to disk, without spines, 3.2mm. Ten small, short, close-set, pointed mouth-papille on each side of the mouth-angle, and one somewhat stouter at the apex ; the two outermost are broadest and most rounded. Mouth-shields large, as broad as long, of a rounded heart-shape. Side mouth-shields stout and wide, broader without than within, where they do not meet. Both they and the mouth-shields are more or less covered by a granulation, which, as well as that of the disk, is © liable to be rubbed off. Under arm-plates axe-shaped, much broader without, where the edge is curved, and with deep re-entering curves on the lateral sides. Side arm-plates thin and microscopically corrugated. Upper arm-plates thin, with a central ridge, about twice as broad as long, much wider without than within, with sharp outer lateral corners and straight sides. Disk round and quite thick closely and evenly covered with minute granules, 12 or 14 in the length of 1mm. Underneath these granules there are fine uniform, overlapping scales, about 5 in the length of 1 mm., among which the radial shields cannot be dis- tinguished. Eight or nine long, slender, tapering, flattened arm-spines, whereof the three uppermost are about 2.3 mm. long and nearly equal, and the other five or six from 2 mm, to1.7 mm. long. Two long, thin, nearly oval tentacle-scales, which are two thirds as long as an under arm-plate. Color in alcohol, pale straw. 46 BULLETIN OF THE Station 172, 240 fathoms, 1 specimen. This species stands very close to O. miliaria of the West Indies, and comes from a similar depth. It seems sufficiently distinguished by the arm-spines, which are more numerous by one or two, and more flattened, showing even a feeble tendency to become spatulate. . OPHIOMYCES Lym. Ophiomyces grandis sp. nov. Plate XIV. Figs. 383 - 385. Special Marks. —¥Eleven sharp, flat arm-spines, set along the whole upper and side edge of the plate, and growing longer from above down to the ninth. Basal under arm-plates, large and squarish, and bearing three long spatula-like tentacle-scales. - . Description of an Individual (off Tristan d’Acunha).— Diameter of disk 6.5 mm. Length of arm about 25mm. Width of arm near disk 2.2mm. Four or five broad, flat teeth, with a curved, cutting edge; the lowest one being much the narrowest. Below these, and still on the jaw-plate, are three spini- form tooth-papille. Then, from apex of mouth-angle, there radiate, on each side, two rows of long, flattened mouth-papille, which completely hide the underlying parts ; each row has five or six papille, of which the innermost one is spiniform, resembling a tooth-papilla ; those beyond, more or less spatula- shaped, grow progressively larger and wider, until the outermost has almost a fan-shape ; all incline more or less downward and outward, so that they overlap, tile fashion. On cutting away the mouth-papille, a small mouth-shield, of an irregular, short diamond-shape, may be seen, together with small triangular side mouth-shields, which nearly meet within. Length of mouth-shield to breadth .7:.7. The jaws are long, narrow, and slender, with very large sockets at their base for the second pair of mouth-tentacles. The first under arm-plate is minute, triangular, and difficult to distinguish ; the second very narrow, closely soldered with surrounding parts, and with deep re-entering curves on the lateral sides ; the fourth plate is four-sided, about as broad as long, much wider without than within, and with deep re-entering curves on the lateral sides ; length to breadth .6:.7. Side arm-plates separated below, meeting narrowly above, not swollen, but clean cut and flaring outward. Upper arm- plates twice and a half as broad as long, shaped like segments of a circle, with a clean curve outward ; near tip of arm they are nearly as long as wide, and form a pointed curve, while the side arm-plates are but slightly flaring and meet above on a line as long as the upper plate. The disk was much torn (as usually is the case), but evidently was covered above and below with fine scales, about 4 in the length of 1 mm., whereof many bore minute, peg-like spines. Eleven arm-spines, increasing rapidly in length from the first to the ninth, then diminishing ; the upper ones are slender, sharp, and little flattened ; the lower ones are broad, flat, sharp, and shaped like a bronze sword ; lengths to MUSEUM OF COMPARATIVE ZOOLOGY. AT that of an under arm-plate, .2, .3, .3, .3, .5, .7, .8, 1, 1.2,.7,.7: .7. The basal under arm-plates, as far as the fifth or sixth, bear on each lateral side three long, flat, spatula-like tentacle-scales, which project over the pore; for some distance beyond there are but two such scales, while a third, trowel-shaped, stands on the edge of the side arm-plate. One third out on the arm there re- mains only the large trowel-shaped scale. Color in alcohol, pale gray. Station, off Tristan d’Acunha, 1000 fathoms, 2 specimens. - The peculiar twisting upward of the arms and disk of Ophiomyces is explained by the absence of radial shields, a want not yet observed in any other genus. It seems, then, that one function of radial shields is to keep the disk in shape, somewhat like the action of the sticks of an umbrella. Ophiomyces spathifer. Plate XIV. Figs. 386-388". Special Marks. — Outer mouth-papille large and paddle-shaped. One flat, rounded tentacle-scale. Ten flattened arm-spines of various shapes, whereof the two lowest are borne on the under arm-plate. Description of an Individual (Station 235).— Diameter of disk 3.5 mm. Width of arm next disk 1.2mm. Three short, narrow, slightly flattened, peg- like teeth, carried on a thick, lumpy jaw-plate, which also bears two long, flat, narrow, spatula-like tooth-papille. On either side of the mouth-angle are two radiating rows, each of about six long, flattened papille, which are imbricated and point downward and outward, so that the entire mouth-angle is hidden by them ; the inner ones are narrow and spatula-like, but outwards they grow rapidly larger, so that the outermost are wide paddle-shaped, or even fan-shaped, their length to extreme breadth being.7: .5. Mouth-shields shaped like a long, sharp, narrow lance-head. Side mouth-shields three-sided, delicate, separated as by a wedge by the mouth-shield, which extends inward considerably beyond them. Within, and indistinctly separated from the side mouth-shields, project the long jaws. These parts are all hidden, and can be seen only by cutting away the mouth-papillz. Under arm-plates small, with re-enteringly curved lateral sides, wider without, where they area little swollen, than within, separated by the side arm-plates, which meet narrowly both above and below, and are highest and most flaring at their outer edge. Upper arm-plates minute (sometimes apparently wanting), twice as long as broad, and appearing like little swellings just outside the juncture of the side arm-plates. The larger part of upper sur- face of arm is thus left uncovered, so that the arm-bones and their muscular bundles may be seen. Disk (as usual in the genus) distorted and pushed up- ward, covered uniformly with minute, thin, translucent, flat scales, without spines; there are about 13 inthe length of 1mm. Ten arm-spines, of which the three highest are equal, slender, narrow and tapering, and as long as any; the next two are of about the same length, but broad and flat, with rounded ends ; the next three similar, but shorter ; the two lowest spatula-like, with ends cut Square off, and carried, not on the side arm-plate, but widely spaced on the 48 BULLETIN OF THE outer part of the under arm-plate ; lengths to that of an arm-joint, .5, .5, .5, .5, .5, .4, .4, .3, .8,.3 : .5. One flat, short, wide tentacle-scale, broader without than within, and, like many of the arm-spines and mouth-papille, microscopi- cally striated. Color in alcohol, disk, gray ; arms, straw. Station 235, 565 fathoms, 3 specimens in bad condition. PECTINURA Forses. Pectinura arenosa sp. nov. Plate XIV. Figs. 392-394. Special Marks. — Nine to eleven short arm-spines. Disk uniformly granu- lated, with about 8 grains in 1 mm. long. No water-pores between under arm-plates. Description of an Individual (Station 162).— Diameter of disk 10 mm. Length of arm about 42mm. Width of arm close to disk2mm. Fifteen short, stout, pointed, crowded mouth-papille, the three outermost being some- what the widest. Mouth-shields rounded triangular, about as broad as long, with a blunt angle inward and outer side straight. Supplementary shield semicircular, and about two thirds as large as the true shield. Side mouth- shields very small, and short, occupying part of the outer angles of mouth- shield, and widely separated within. First under arm-plate wide and large, and nearly semicircular though the inner side is not quite straight ; those be- yond are as broad as long. There are no water-pores between the plates. Side arm-plates flat and not swollen, separated above and below. Upper arm- plates short rounded oval; somewhat broader than long. Disk somewhat angular and slightly swollen, closely covered above and below, except the mouth-shields and side mouth-shields, with a fine granulation, about 8 grains in the length of 1 mm. Genital openings extending from mouth-shield about two thirds the distance to the margin. Nine to eleven short, stout, somewhat flattened peg-like arm-spines, all about half as long as the side arm-plate, except the lowest, which equals it. Two small rounded tentacle-scales on the side arm-plate, whereof that on the interbrachial side overlaps the base of the lowest arm-spines. Color in alcohol, disk pale yellowish brown, above ; arms darker, with irregular belts of black and yellowish brown. Station 162, 38 fathoms, 6 specimens. This species stands between P. spinosa and P. infernalis. Pectinura heros sp. nov. Plate XIV. Figs. 389-391. Special Marks. — Three very short arm-spines, low down on the side arm- plate. No pores between lower arm-plates. Description of an Individual (Station 191).— Diameter of disk 22 mm. Length of arm about 100 mm. Width of arm close to disk without spines MUSEUM OF COMPARATIVE ZOOLOGY. 49 4mm. Fifteen small, close-set mouth-papille to each angle, whereof the two or three outer ones on each side are flat, rounded, and larger than the rest, which are pointed ; there are two just under the teeth, and sometimes two supplementary below and outside these. Mouth-shields long heart-shaped, with a rounded angle within ; length to breadth 3: 2.2. Sometimes a rudimentary supplementary piece may be seen, just outside. Side mouth-shields three- cornered and small, oceupying only the outer corners of the mouth-shield. Under arm-plates about as wide as long, bounded without by a curve, within by a truncated angle, and laterally by re-entering curves. Side arm-plates short, with rounded edges, meeting neither above nor below. Upper arm- plates broad, highly arched, closely overlapping, with outer and inner edges nearly straight. Disk flat and angular, closely and evenly covered with very fine granules, 7 or 8 in the length of 1 mm., except the radial shields and one or more plates along the margin. “Radial shields egg-shaped, longer than broad, with outer and inner ends much rounded ; length to breadth 3.7:2. Lower interbrachial space covered by same granulation as above, extending even to the mouth-angle, but not on mouth-shields. Genital opening long, extending from mouth-shield to margin of disk. Three short, small, blunt arm-spines standing low on the side arm-plate, and about half as long as a joint. One round tentacle-scale. Color in alcohol white. Station 191, 800 fathoms, 1 specimen. This species stands as near P. stellata as to any ; there are, however, no pores between the under arm-plates, and but three short arm-spines. The only oc- casional presence of rudimentary supplementary mouth-shields points once more to the very close connection between Ophiopeza and Pectinura. Pectinura maculata Vit. Pectinura maculata. Proc. Bost. Soc. N. H., XII., 1869, p. 388. Queen Charlotte’s Sound, New Zealand, 10 fathoms, 5 specimens. Pectinura rigida Lym. Pectinura rigida. Bull. Mus. Comp. Zool., I11. 10, 1874, p. 224. Fiji Islands, 2 specimens. Pectinura stellata Lrx. Pectinura stellata. Addit. ad Hist. Oph., Pt. III., 1869, p. 33. Station 208, 18 fathoms, 1 specimen, Pectinura gorgonia Lrr. Pectinura gorgonia. Addit. ad Hist. Oph., Pt. III., 1869, p. 33. Fiji Islands, 1 specimen. VOL. VI. NO. 2. 4 50 BULLETIN OF THE OPHIOPEZA PETERS. Ophiopeza aster sp. nov. Plate XIV. Figs 395-397. Special Marks. — Disk densely and finely granulated above and below, in- cluding the mouth-angle. Description of an Individual (Station 142).— Diameter of disk, 11 mm, Length of arm, 33mm. Width of arm close to disk, 2mm, Teeth narrow, sharp and lanceolate ; the two lowest usually split in two. The apex is occu- pied by a bunch of three or four short, crowded, spiniform tooth-papille ; and on each side of the mouth-angle is a close line of small mouth-papille, whereof the inner ones are bead-like, while the two outermost are wider and somewhat flattened. The small, rounded mouth-shields and the.side mouth-shields are completely covered by a close granulation. First under arm-plate about half as large as those beyond, of a heart-shape, with the point inward ; the rest are rather small, somewhat broader than long, much wider without than within, having the outer side curved, lateral sides re-enteringly curved and a truncated angle within. Side arm-plates small, clinging close to arm, widely separated above, nearly meeting below. Upper arm-plates four-sided, twice as broad as long, much wider without than within, with outer side gently curved and lat- erals straight. Disk pentagonal, flat, densely and uniformly covered with an extremely fine granulation, 20 or 25 grains in the length of 1 mm.; this gran- ulation extends over the entire mouth angle quite to the bases of the mouth- papilla. Six very short arm-spines, growing longer from above downward ; the upper ones are rounded and peg-like ; the lowest ones somewhat flattened, and scarcely more than half as long as a joint. One oval tentacle-scale. Color in alcohol, light greenish gray. Station 142, 150 fathoms, 6 specimens. OPHIOTHRIX Mitt. & Troscu. Ophiothrix aristulata sp. nov. Plate XV. Figs. 421-424. Special Marks. — Ten moderately stout, feebly thorny, scarcely tapering arm- spines. Disk, except the large radial shields, densely set with short, slightly rough spines. Description of an Individual (Station 142).—— Diameter of disk 14 mm. Width of arm near disk 3mm. There are about thirty tooth-papille which are pointed, and are arranged, as ysual, in a vertical oval, the exterior line on either side composed of ten or eleven longer ones, while a similar number of shorter ones, arranged in twos at the centre, and in a single line above and be- low, fill closely the middle space. Three short, thick, squarish teeth. Mouth- MUSEUM OF COMPARATIVE ZOOLOGY. 51 shield well marked, of a transverse diamond-shape, with rounded corners. Side mouth-shields thick and slightly swollen, rather wide, nearly or quite meeting within, tapering gently inward. Under arm-plates somewhat wider than long, with a wide curve without, short re-enteringly curved laterals, and straight inner laterals sloping towards the median line. Side arm-plates presenting a moderately prominent spine-crest. Upper arm-plates wider than long, slightly overlapping, of a transverse diamond-shape, with corners rounded or truncated ; each plate has a median ridge, which gives to the upper arm a carinate look. Disk thick and strongly lobed in the interbrachial spaces ; its upper surface occupied chiefly by large radial shields, which are long triangular, with a length to breadth of 5:3 ; they unite without, where each has a lobe projecting over the arm, separated within by a narrow wedge of scales bearing one or two rows of short, slightly rough spines: similar but somewhat longer spines densely clothe the centre and interbrachial spaces, passing over the margin and investing the outer portion of the naked surface below ; the longest spines are 1.7 mm. Ten moderately stout, scarcely sapering, somewhat flattened, translucent arm- spines, bearing feeble thorns on their edges; the uppermost and lowest are minute, the rest diminish in length from the third downward ; lengths to that of an under arm-plate, .8, 3.6, 4.6, 3.6, 3, 3, 2.6,2,1,.8:1. The first tentacle- pore has no scales ; those beyond have a minute lip-like one in the angle of the under and side arm-plates. Color in alcohol, above, pale purplish pink, the side arm-plates and outer edges of radial shields marked with darker ; below, much paler. Station 142, 150 fathoms, 12+ specimens. Station 161 (var. with coarser spines), 38 fathoms, 2 specimens. Station 163 (var.), 120 fathoms, 5 speci- mens. The species is readily distinguished from O. capensis by lacking the black stripe on the arm, and by having arm-spines serrated their whole length. Ophiothrix capillaris sp. nov. Plate XIV. Figs. 401-404. Special Marks.— Very large, with nine very delicate, translucent arm-spines, whereof the upper ones are extremely long. Disk set with minute stumps, which are few and scattered on the large radial shields. Description of an Individual (Station 204).— Diameter of disk 22 mm. Width of arm near disk, 4.8 mm. The vertical oval has over fifty tooth-papille of various sizes, those in the lower half being minute, crowded, and grain-like, while those on the margin of the upper half are large and thiek, and project beyond the median papilla. Four flat teeth, with rounded cutting edge ; the uppermost and lowest narrowest. Mouth-shields small, much broader than long, bounded’ by a gentle curve without and an obtuse angle within ; length to breadth .8 : 1.8. Under arm-plates small, narrow, about as long as broad, eight-sided, with angles mofe or less rounded and lateral sides a little re-enter- ingly curved. Side arm-plates with a well-marked spine-ridge. Upper arm- 52 BULLETIN OF THE plates about as broad as long, of a short diamond-shape, with angles rounded, rising on the median line ina low ridge and microscopically tuberculous. Disk round and flat, scarcely lobed in interbrachial spaces, more or less closely heset above and below with minute stumps bearing an irregular crown of thorns; on the radial ‘shields they are much more scattered, smaller, and less thorny, and next the genital openings there are none, The radial shields, whose out- lines are distinguishable through their covering, are triangular and very large, _ with a small lobe where they unite over the arm ; inwardly they diverge, and sometimes again bend together so as nearly or quite to reunite; length to breadth 9: 4.5. On joints next disk there are nine slender, glassy, translucent, slightly flattened feebly thorny spines, whereof the uppermost are extremely long and elegant; those below progressively shorter ; lengths to that of an under arm-- plate, 15.5, 15, 13, 9, 7, 6, 5, 3,1.7: 1.7. One small, blade-like tentacle-scale in the angle of the under and side arm-plates. Color in alcohol, above, pale brownish pink ; below, very pale yellowish brown ; along upper side of arm is a wide, brown stripe, whose edges are darkest. Station 204, 100-115 fathoms, 3 specimens. Cebu ; 100 fathoms. O. capillaris belongs near O. comata and O, Suensonii. It has an arm-stripe like that of the former, but has little stumps on the disk instead of hair-like spines. Ophiothrix berberis sp. nov. Plate XV. Figs. 425-428. Special Marks. —Seven short, blunt, much flattened, strongly toothed arm- spines. Radial shields and interbrachial spaces below nearly or quite naked. Rest of disk set with short stumps bearing a crown of thorns. Description of an Individual (Station 192). — Diameter of disk 9mm. Width of arm near disk 2.6mm. Length of arm about 58mm. The vertical oval has about seventeen stout, blunt, nearly equal tooth-papilla, whereof the mar- ginal ones are scarcely longer than those in the middle. Three squarish, rather thin teeth. Mouth-shields broader than long, with an obtuse angle inward and a gentle curve without ; length to breadth, 1 : 1.5. Side mouth-shields rather narrow, slightly swollen, wider without than within, where they scarcely meet. First under arm-plate unusually large, nearly equalling the second, squarish, with rounded corners and an obtuse angle within. The plates increase in size to the seventh, which is broader than long, bounded without by a wide curve, and within by a truncated angle ; length to breadth .7 : 1.1. Side arm-plates furnished with a low thick spine ridge. Upper arm-plates transverse diamond- shaped, overlapping, having outer angle rounded and inner one truncated ; length to breadth .7 : 1.4. Disk rather flat, lobed in the interbrachial spaces, which, below, are nearly naked, as are the radial shields, while the remainder of the upper disk is densely covered with short, minute stumps, each bearing a crown of three or four thorns, or, rarely, a fork of two longer thorns. Radial shields long triangular, just touching without, diverging gently inward ; length to breadth 2.7 : 1:7. Seven, short, blunt, much flattened arm-spines, bearing MUSEUM OF COMPARATIVE ZOOLOGY. 53 strong thorns on their edges; the second one is longest, and those below grow gradually shorter ; lengths to that of an under arm-plate, 2.3, 3.5, 2.5, 2.2, 1.7, 1.5,.7.:.7. One minute tentacle-scale. Color in alcohol, above, disk pale greenish gray, arms of a faint pink. Station 192, 129 fathoms, 1 specimen. Station, Cebu, Philippines, 95 - 100 fathoms, 1 specimen. Ophiothrix csespitosa sp. nov. Special Marks. — Nine short, stout, much flattened, strongly toothed arm- spines. The puffed disk and small radial shields are set with short spines. Upper arm-plates transverse diamond-shaped, with lateral angles sharp. - Description of an Individual (Port Jackson).— Diameter of disk 7 mm. Length of arm 28 mm. Width of arm near disk 1.5. The vertical oval has about sixteen stout, blunt, nearly equal tooth-papille, whereof four or five are on the median line, and nearly as large as those on the margin. Four rather thin, squarish teeth, with a cutting edge making an obtuse angle. Mouth- shields small, closely joined to surrounding parts, broader than long, of a trans- verse, rounded oval shape, having a curve without and a very blunt, obtuse angle within. Side mouth-shields narrow, wider without than within, where they meet. Under arm-plates with ill-marked outlines of a rude, transverse oval form, with a curve without, lateral sides a little indented and the inner side vaguely angular. Side arm-plates with a low spine ridge. Upper arm-plates much wider than long, transverse diamond-shape, with lateral angles sharp and the outer one rounded ; length to breadth .5 : 1.1. Disk thick, and pufted in the interbrachial spaces, thickly set near the margin with short, stout, stump~ like spines rough at ends and sides, the longest .5 mm. in length. Towards the centre the spines grow fewer, and the middle region has scarcely any, so that the rounded overlapping scaling is conspicuous ; next the mouth-shields, also, there are no spines. Radial shields small and triangular, much obscured by the short spines. Nine short, translucent, rather stout, blunt, flattened arm- spines, bearing pretty strong thorns on their edges ; lengths to that of an under arm-plate, .8, 1.5, 1.8, 1.7, 1.3, 1.1, .9, .7,.4 : .5. One minute tentacle-scale at angle of under and side arm-plates. Color in alcohol, above, disk faint green- ish ; arms banded with lighter and darker yellowish brown. ‘Station, Port Jackson, 2-10 fathoms, 3 specimens. In its disk this species resembles O. triglochis, but the arm-spines are much flatter and more toothed, and the upper arm-plates of a different shape. Ophiothrix violacea Miu. & Troscn. Ophiothriz violacea. Syst. Asterid., p. 115. Off Brazil, 7-20 fathoms, 12+ specimens. Station 36, off Bermuda, 32 fathoms, 3 specimens. Fernando Noronha (same species ?), shallow water, 1 specimen, 54 BULLETIN OF THE Ophiothrix Liitkeni? Wyv. Tom. Ophiothrix Liitkeni. Depths of the Sea, 1872, p. 100. Station 75, 450 fathoms, 1 specimen (young). Ophiothrix propinqua Lym. Ophiothrix propinqua. Proc. Bost. Soc. Nat. Hist., VIIL., 1861, p. 83. Tongatabu, 18 fathoms, 3 specimens (red var.). Fiji, Levuka Reefs, 2 speci- mens. | Ophiothrix purpurea v. Marrens. Ophiothrix purpurea. Monatsber. Kon. Akad., 1867, p. 346. Station 176, 1450 fathoms [error? Sta. 177, 63 fms. ?], 3 specimens. Banda, 1 specimen. Ophiothrix nereidina Mutu. & Trosc#. Ophiothriz nereidina. Systerid. Ast., p. 115. Zamboanga, Philippine Isl., 10 fathoms, 4 specimens. Ophiothrix stelligera Lym. Ophiothriz stelligera. Bull. Mus. Comp. Zoél., III. 10, p. 237. Aug. 7, 1874, 6 specimens. Station 186, 8 fathoms, 1 specimen. Arafura Sea, 1 specimen (same species?). Zamboanga, 10 fathoms, 1 specimen. Ophiothrix Suensonii Lrx. Ophiothriz Suensonii. Vid. Meddel., 1856, p. 16. Station 36, 32 fathoms, 2 specimens. Ophiothrix pusilla Lym. Ophiothriz pusilla. Bull. Mus. Comp. Zodl., III. 10, p. 235. Station 208, 18 fathoms, 3 specimens. Ophiothrix longipeda Mutt. & Troscu. Ophiothrix longipeda. Syst. Asterid., p. 113. Station 186, 8 fathoms, 2 specimens. Ternate Shore, 1 specimen. 7 Aug., 1874, 1 specimen. Station 188, 28 fathoms, 2 specimens. Tongatabu, 18 fathoms, 1 specimen (same species?). Amboyna, 100 fathoms, 10 specimens (same species?). Zamboanga, 10 fathoms, 1 specimen. Ophiothrix galatez? Lrx. Ophiothriz galatea. Ophiurid. Nov. Descr., 1872, p. 108. Tongatabu, 18 fathoms. ‘MUSEUM OF COMPARATIVE ZOOLOGY. 5d Ophiothrix striolata GRUBE. Ophiothrix striolata. Verhandl. Schlesisch. Ges., 1867, Pt. III. p. 99. Station 208, 18 fathoms, 1 specimen. Fatcabsasase Philippines, 10 fathoms, 1 specimen. Ophiothrix Martensi Lym. Ophiothrix Martensi. Bull. Mus. Comp. Zool, ILI. 10, p. 234. “ Aug. 7, 1874, 4 specimens. Ophiothrix exigua Lym. Ophiothrix exigua. Bull. Mus. Comp. Zool., [11]. 10, p. 236. Station 188, 28 fathoms, 1 specimen. Station 208, 18 fathoms, 1 specimen. Ophiothrix ciliaris? Mui. & Troscu Ophiothrix ciliaris. Syst. Asterid., p. 114, Lym. Bull. Mus. Comp. Zodl, III. 10, p. 233, Pl. IV. figs. 29 - 32. Cebu, 95 - 100 fathoms, 1 specimen. Ophiothrix triglochis Miu... & Trosca. Ophiothrix triglochis. Syst. Asterid., p. 114. Simon Bay, 5-18 fathoms, 3 specimens. OPHIOCHITON Lym. Ophiochiton lentus sp. nov. Plate XIV. Figs. 398-400. Special Marks. —'Three stout arm-spines. Under arm-plates thickened, but not forming a distinct ridge. Scaling of disk smooth and uniform. Description of an Individual (Station 171). —Diameter of disk 13 mm. Width of arm close to disk 2.6mm. There are eleven short, sharp, stout, close-set mouth-papille on each angle, the two outermost and the one at the apex being a little larger than the rest. Mouth-shields about as broad as long, of a rounded heart-shape. Side mouth-shields extremely narrow, bent, wider without than within, where they meet. Under arm-plates large, swollen but not ridged, wider without than within, with lateral sides re-enteringly curved. Side arm- plates short and stout, with a low thick spine-ridge. Upper arm-plates twice as broad as long, of a fan-shape, with inner angle truncated, or a diamond-shape with much rounded angles. Disk round, smooth, and flat, covered with small, pretty uniform, rounded, overlapping scales, 2 or 3 in the length of 1mm. Radial shields small, twice as long as broad, with much rounded corners, separated their entire length hy two large round scales ; length to breadth2:1. Interbrachial spaces below covered with scaling similar to but finer than that above. Genital open- ings. long, extending from outer corners of mouth-shield, where there are a few 56 BULLETIN OF THE minute papille, to margin of disk. Three stout, blunt, cylindrical, tapering, nearly equal arm-spines, about as long as an arm-joint. Two round, flat, ten- tacle-scales on the side arm-plate, whereof the one next the under arm-plate is much the smaller. Color in alcohol, pale gray. Station 171, 600 fathoms, 1 specimen. OPHIOGLYPHA Lym. Ophioglypha meridionalis sp. nov. Plate XVI. Figs. 447 - 449. Special Marks.-—Disk rather flat, covered with large imbricated scales. Arm-comb of minute bead-like papille, scarcely to be seen above, but con- tinuous along edge of genital scale. Three peg-like arm-spines less than half as long as a joint. Only one tentacle-scale beyond the mouth-tentacles. Description of an Individual (Station 320). — Diameter of disk 4mm. Length of arm about 12mm. Width of arm close to the disk .7 mm. Five small, short, broad, flat, close-set mouth-papille on each side of the mouth-angle, and one pointed and similar to the teeth at the apex. Mouth-shields somewhat swollen, about as broad as long, with a curve without and an obtuse angle in- ward. Side mouth-shields short, straight, meeting by their full width within, occupying only the inner angle of mouth-shield. First under arm-plate blunt heart-shaped, quite as large as, or larger than, the second, which is pentagonal, with inner angle truncated, outer side gently curved, and laterals re-enteringly curved ; one third out on the arm the under plates are small, much wider than long, bounded by a broad curve withont and with a little peak inward. Side arm-plates large and thick, meeting broadly below beyond the second arm- plate, and touching above beyond the third plate. Upper arm-plates long wedge-shaped, with a clean curve outward and a sharp angle within. Disk rounded, rather flat and only a little arched above, covered by large slightly swollen scales, whereof the primary plates form a conspicuous rosette, radiating from which there usually is, in each interbrachial space, a row of three over- lapping scales. Radial-shields as broad as long, ‘sunken, rounded, with a faint angle inward ; joined without, separated by a wedge-scale within; they are smaller than the large disk-scales. Below, the scales are similar, eight or nine in each interbrachial space. Papille along edge of genital scale minute, bead-like, and continuous; only one or two, and sometimes none, can be seen from the upper surface. Three small, nearly equal, peg-like arm-spines, less than half the length of a side arm-plate. Five small, close-set tentacle- scales to pores of mouth-tentacles, three on one side and two on the other ; the pores beyond have but onesmall, rounded scale. Color in alcohol, straw. Station 320, 600 fathoms, 1 specimen. The single specimen, though well characterized, was perhaps not fully grown. It is the southern cousin of O. robusta, from which it differs in shorter arm-spines, more swollen disk-scales, smaller mouth-papillz, and fewer tentacle- scales, MUSEUM OF COMPARATIVE ZOOLOGY. 1 oF OPHIACANTHA .MUttt. & Troscu. Ophiacantha discoidea sp. nov. Plate XV. Figs. 405 - 407. Special Marks. — Seven or eight slender, translucent, nearly smooth arm- spines. A small spine-like tentacle-scale. Disk densely set with minute stumps crowned with thorns. Description of an Individual (Station 190). — Diameter of disk, 4.7 mm. Arms broken ; they were plainly long, because, in their first 15 mm. there was scarcely any tapering. Width of arm near disk 1mm. Three cylindrical, blunt, peg-like mouth-papillz on each side, and a similar but longer one at apex of mouth-angle. Teeth longer than wide, with a rounded cutting edge. Mouth-shields broader than long, regular heart-shaped, with point inwards ; length to breadth, .7:1. Side mouth-shields very wide without, and overlap- ping the first under arm-plate, but tapering to a thin point within, where they scarcely meet. First under arm-plate longer than broad, and somewhat over- lapped by side mouth-shields ; the plates just beyond are much wider than long, of a wide axe-shape, with a broad curve without, short re-entering curves on the sides, and an obtuse angle within. Side arm-plates meeting above and below, stout and flaring, with a strong spine-crest. Upper arm-plates fan- shaped, with the angle inward ; widely separated. Disk nearly round, a little puffed, closely and evenly set, except in the middle, with very short micro- scopic stumps crowned with 3 or 4 littlethorns. No scales or radial shields ap- pear in the alcoholic specimen. Seven or eight slender, pointed, translucent, nearly smooth arm-spines, whereof the two uppermost are nearly as long as two joints ; while those below gradually diminish in length to the lowest, which is two thirds as long as a joint. One narrow, pointed tentacle-scale. Color in alcohol, pale brownish gray. Station 190, 49 fathoms, 1 specimen. This species stands nearest, perhaps, to O. cosmica, from which it is distin- guished by different under arm-plates, smaller side mouth-shields, stouter disk- stumps, and a very narrow spine-like tentacle-scale. Ophiacantha Valenciennesi sp. nov. Plate XV. Figs. 408-410. | Special Marks. — Disk ‘evenly granulated above. Seven long, slender, much flattened arm-spines. Outer mouth-papilla spatula-like and covering the pore of the mouth-tentacle. Description of an Individual (Station 192).— Diameter of disk 11 mm. Length of arm 50mm. Width of arm near disk 3mm. Twelve mouth-papille to each angle ; of these the outermost one on either side is wide, like a short spatula, and is plainly the scale of the mouth-tentacle ; the next four papille 58 BULLETIN OF THE are sharp and peg-like, the pair at apex of angle are thickened and conical. Five flat teeth, a little longer than wide, with a curved cutting edge. Mouth- shields long heart-shaped, or broad spear-head shaped ; length to breadth 1.5: 1.2. Side mouth-shields large and three-sided, wide without, tapering inward, where they nearly or quite meet. First under arm-plate small and wider than long ; plates beyond, wide pentagonal, with outer side gently curved, laterals re-enteringly curved, 4nd inner angle so obtuse and rounded as to be almost a gentle curve. Side arm-plates barely meeting below, separated above, rising in a thick abrupt spine-ridge. Upper arm-plates small, thick, and fan-shaped, with the angle inward. Disk thick and puffed, covered above by an even granulation, 9 or 10 grains in the length of 1 mm. On removing these, there is disclosed a smooth coat of very thin scales, about 5 in the length of 1 mm., which cover the radial shields, except their outer ends ; interbrachial spaces below without grains, and covered with scales still finer than those above. Seven slender, much flattened arm-spines, slightly rough on the edges; the uppermost one extremely long, sometimes equal to five arm-joints, diminishing to the lowest, which is longer than one joint. Two large, oblong, slightly pointed tentacle-scales. Color in aleohol, pale brown above, much lighter below. Station 192, 129 fathoms, 1 specimen. Ophiacantha Normani sp. nov. Plate XV. Figs. 414-416. Special Marks. — Disk distinctly scaled and sparsely granulated, and with small, separated radial shields. A single row of grains along the outer edge of the basal upper arm-plates. Four smooth, slender spines, the upper ones longest. Description of an Individual (Station 232).— Diameter of disk 12.5 mm. Length of arm about 40mm. Width of arm next disk 2.6mm. Seven widely spaced, cylindrical, tapering, peg-like mouth-papille, three on each side, and one at apex of mouth-angle. Mouth-shields a little broader than long, thick and _ Square, with a little peak without and within ; length to breadth 1: 2. Side mouth-shields long and narrow, their outer end wedged between the first and second under arm-plates ; not quite meeting within. First under arm-plate well marked, of a rounded triangular shape, with the point outward; third plate, . and those just beyond it, broader than long, bounded without by a curve, on the sides by re-entering curves, and within by an angle; length to breadth (4th plate) 1.3: 1.7. Side arm-plates with a swollen spine-ridge, meeting below, but separated above, stout, and, like the under plates, microscopically tuber- culouss Upper arm-plates about as broad as long, short wedge-shaped, with outer side curved and a blunt angle within ; the first three or four have, along their outer margin, a single row of rounded grains, Disk flat, somewhat angular, covered with well marked, pretty equal, overlapping scales, whose sur- face is sparsely set with rounded grains, similar to those of the upper arm-plates ; interbrachial spaces below similarly covered, except that the scales are smaller MUSEUM OF COMPARATIVE ZOOLOGY. 59 and obscured by skin. Radial shields small, ovoid, as long as broad, widely separated by a wedge of scales ; length to breadth 1.7: 1.3. Genital openings wide, and extending quite from the mouth-shield to the disk margin. Four smooth, cylindrical, rather slender, blunt, tapering arm-spines, whereof the lowest is as long as an arm-joint, the two upper ones as long as a joint anda half, and the third intermediate. One rather large oval tentacle-scale. Color in alcohol, gray, with arm inclining to straw. ‘ Station 232, 345 fathoms, 12+ specimens. Station 235, 565 fathoms, . 1 specimen. Ophiacantha abnormis sp. nov. Plate XV. Figs. 411-413. Special Marks. — Mouth-angles elongated, bearing, toward the apex, 12 or 14 slender, pointed papilla. Six long, smooth, slender arm-spines. Disk sparsely set with very short spines. Description of an Individual (Station 207).— Diameter of disk 11 mm. Length of arm, which is very attenuated near its end, 73 mm. Width of arm close to disk, without spines, 25 mm. Mouth-angles elongated, having no papille on their outer part near the mouth-tentacles, but on their inner portion bearing 4 or 5 slender, spaced papille on each side, and a cluster of 3 or 4 at the apex. Teeth wide and large, with a broad cutting edge. Mouth-shields broad triangular, with a small peak on the outer edge, and blunt angle within. Side mouth-shields short and extremely narrow, just meeting within. Under arm-plates thin and sunken, pentagonal, with a broad angle inward, outer edge straight, and deep re-entering curves on the lateral sides. Beyond the third, they are separated by the side arm-plates, which meet below and above and have a high, wide spine-ridge. Upper arm-plates triangular, some- what swollen, with an angle inward, sharp lateral corners, and broad nearly straight outer edge, which on the basal plates bears two minute spines. Disk flat, having re-entering curves in the interbrachial spaces, and rather sparsely set with minute, short, blunt spines, which are fewer below. The outer ends of radial shields are exposed over the base of each arm. Genital openings long and large, extending from mouth-shield to disk margin. Six long, slender, smooth, cylindrical, tapering arm-spines, of which the two upper ones are as long as two arm-joints, thence diminishing in length to the lowest, which is about as long as half a joint. Pores large and tentacles very long ; on basal ones are two scales, of a pointed oval shape ; on those beyond, only one. Color in alcohol, straw. Station 207, 700 fathoms, 12+ specimens. Station 210, 375 fathoms, 5 specimens. In its elongated mouth-angles, this species somewhat resembles O. hirsuta, but its arm-spines are smooth and in all ways different. 60 BULLETIN OF THE NOTE ON THE STRUCTURE OF ASTROPHYTIDA. In very early youth the Astrophytons bear a close resemblance to true Ophiurans, but they rapidly change with growth. Their structure will be more fully treated in the main work, and only two or three points of differ- ence will here be suggested. First, as to the arm covering. The young tip of an Astrophyton twig has the side arm-plates quite encircling it (Fig. 495), just as in an Ophiuran ; but already at the base of the same twig this plate is quite subordinate (Fig. 494 7), while at the base of the arm (Fig. 493 7) it occupies only the under surface, while the arm has risen in a high arch above it. It is not otherwise in the simple-armed Astroschema (Fig. 4917). The upper arm-plates have no regular form, or stated mode of division ; but doubtless they are represented by a casing of very irregular scale-like pieces, to be found on the terminal branches of Astrophyton, and in the narrow belts of broken plates found in A stroschema (Fig. 491). The under arm-plates are extremely variable ; in the type of Euryale asperum they are essentially in one piece, and are constant to the end of the branches (Fig. 499 4), while for the type of Astrophyton costosum they are quite wanting, except perhaps the first one (Fig. 4974), and are replaced by the large side arm-plates (Fig. 497 7) ; in the cold-water Astrophytons, such as A. Agassizii, they are plainly distinguished in the young, though divided in three pieces (Fig. 492 2, h). To such a structure of arm-plates the nearest approach among Ophiurans would perhaps be Ophiomyza. Secondly, as to the arm-spines. There are found, at the extreme tip of a twig of Astrophyton (Fig. 495), little hooklets on the side arm-plates ; when the arm has risen above the plate, and become quite distinct from it, there are found two or more large hooks (Fig. 494 q), which are the homo- logues of tentacle-scales, and which, nearer the base of the arm, usually become blunt spines (Fig. 493 q). In addition to these there are found on the twigs, in the true Astrophytons, Astroclon, Astrocnida, and among the simple-armed, in Astrogomphus, Astroporpa, Astrochele, and Astrotoma, two zones or belts of raised grains, each grain bearing a hooklet (Fig. 494). These belts of hook- bearing grains are therefore characteristic of a group among Astrophytide ; while another is destitute of them, as Euryale asperum (Figs. 500, 501), Tri- chaster, Astroceras, Astroschema (Fig. 491), Ophiocreas, and Astronyz. Thirdly, the mouth-shields among Astrophytons are quite subordinate, al- though so important among Ophiurans. Frequently there is but one (Fig. 492 a), and the position is very variable. The side mouth-shields, on the con- trary, are usually very prominent (Figs. 492, 497, 499 b) ; so large are they in Trichaster that Miller and Troschel mistook them for a mouth-shield cut in two. The entirely different structure of Euryale asperum as exhibited in the figure (499), and especially the elongated side arm-plates (Fig. 501 7), absence of hook-bearing grains, and distinct build of mouth and under arm-plates: makes it advisable to remove the species from Astrophyton and restore to it the name Euryale. It is a question, also, whether the tropical Astrophytons MUSEUM OF COMPARATIVE ZOOLOGY. 61 should not be generically distinguished. I have already shown, in considering those of the Hassler Expedition, the very different character of the arms (Figs. 496, 498), and the arrangement of their underlying hard parts is cer- tainly quite different in the two (Figs. 492, 497). ASTROTOMA Lym. Astrotoma Murrayi sp. nov. Plate XVIII. Figs. 474 - 476. Special Marks. — Large tubercles, or smooth warts, on upper side of disk. No hooklets on belts of grains on arms, except close to their tip. Clusters of grains in interbrachial spaces next mouth. Description of an Individual (Station 194).— Diameter of disk 29 mm. Length of arm 280 mm. Width of arm near disk 7 mm. Height of arm near disk 7mm Apex of mouth-angle, embracing all the region of the jaw-plate, densely set with short, sharp, nearly equal, spine-like papille, thirty or more in number, and arranged in transverse rows of three or four. Lower surface and a part of the sides of the protuberant mouth-angles closely set with rounded and sometimes elongated grains. One round madreporic mouth-shield, 1.5 mm, in diameter, lying on the margin of the horizontal mouth-region, where it is separated from the vertical interbrachial space by a fold of skin stretched be- tween the bases of the arms. Arms high, and tapering gradually to their tips, covered above and on the sides by belts of granules alternately raised and sunken. In the former the granules are larger and more distinct, and are more or less regularly arranged in four rows, whereof two at tip of arm bear minute, simple hooks, which, however, are soon rubbed off. In the latter, the granules are minute and arranged as a smooth pavement, in which appear many oblong holes or depressions. On its under surface the arm is covered by a cross- wrinkled, calcified skin, on which are scattered granules. Disk flat and angu- lar, with re-entering curves in the interbrachial spaces; the radial shields, whose outlines are vaguely defined, are broad, and run nearly or quite to the centre. The upper surface is covered by a smooth pavement of small, soldered grains, among which appear small oblong depressions, and on whose surface are scattered a few. large, smooth tubercles. The interbrachial spaces below are covered by a clump of large, coarse grains ; at the inner end of each of these spaces is a deep, transverse hollow, at either extremity of which is a short, genital opening. Between the mouth-slit and lower margin of disk there are no tentacle-scales ; but, beyond, each pore has four, rarely five, stout, smooth, peg-like scales, lying side by side, arid nearly as long as an arm-joint ; nearer tip of arm there are but three. Color in alcohol, reddish brown, the disk tubercles and clumps of grains about mouth being darker. Station 194, 200 fathoms, 1 specimen. “ 62 BULLETIN OF THE ASTROCERAS * gen. nov. Disk and arms covered with smooth, soft skin. Disk small ; its interbra- chial outlines re-enteringly curved; radial shields narrow and rather high, running nearly to centre. Arms somewhat knotted by a contraction between each pair of joints. Upper arm-plates divided in halves like high ribs, bearing a jointed spine at their upper end. Side arm-plates, towards middle of arm, having a long process to which are articulated the two spine-like tentacle- scales. Teeth. A clump of grains on sides of mouth- angles, answering to mouth-papille. Two vertical genital openings. Astroceras stands next Ophiocreas and Astroschema. By its peculiar elon- gated side arm-plates bearing spine-like, rough tentacle-scales, and the large spines on the upper surface of the arm, it resembles the branching Ewryale asperum. Astroceras pergamena sp. nov. Plate XVIII. Figs. 478 -480. e Special Marks. — The smooth skin is translucent, allowing the underlying parts to be seen. The upper ends of the halves of the upper arm-plates pro- ject, and bear a stout spine. Tentacle-scales thick, rough ended, and nearly equal in size. On the sides of the mouth-angle are elongated grains answering to mouth-papille. Description of an Individual (Station 235).— Diameter of disk 19 mm. Length of arm about 100 mm. Width of arm at base 2 nm. ; height of same 2.5mm. High up on the sides of the mouth-angles are elongated grains, irreg- ularly arranged and answering to mouth-papille, while at the apex is the low- est tooth, flat and shaped like a wide spear-head. Mouth-shields very small, triangular, with a rounded angle inward and outer edge straight. Side mouth- shields very large and swollen, narrower without, meeting broadly within ; both they and the mouth-shields are obscured by skin. Under arm-plates small, and squarish, and occupying only a part of the length of a joint. Side arm- plates nearly or quite meeting below, swollen and rounded, with a small pro- jection to carry the two spine-like tentacle-scales ; further out, on the arm, this projection is much elongated, forming an articulating process. Upper arm- plates represented by two rib-like ridges, which do not meet above, but project over the upper level of the arm, and bear a large, club-like, rough spine about 1.2 mm. long. Disk thin, and with deep constrictions in the interbrachial spaces. The smooth translucent skin allows the long and narrow radial shields to be seen ; they are pointed within where they do not meet, and are separated their entire length; at their outer end they are elevated and carry a jointed spine, similar to that of the arms. The first pair of arm-pores has no tentacle- scales ; but those beyond have two, which are thick and club-shaped, with * dorhp, star; xépas, horn. MUSEUM OF COMPARATIVE ZOOLOGY. 63 rough ends, and, unlike those of Astroschema, are nearly equal in size, and not much elongated towards the middle of the arm, where they bear bunches of minute hooks on their ends, and have a pedunculated look, owing to the elongation of the side arm-plates. Color in alcohol, light yellowish brown. Station 235, 565 fathoms, 1 specimen. OPHIOCREAS Lym. In Ophiocreas and Astroschema the mouth gives almost no specific indica- tions. It is by the character of the skin, or by the nature of its granulation, the thickness and Jength of the arms, their comparative height and breadth, and the form of the tentacle-scales and of the radial shields, that we get good specific marks. | Ophiocreas carnosus. Plate XVI. Figs. 435 - 438. Special Marks. — Animal covered by a smooth, soft, wrinkled skin. Tenta- cle-scales like rough-ended but not clubbed spines, which are short even at middle of the arm. Description of an Individual * (Station 308).— Diameter of disk 15 mm. Length of arm 200 mm. Width of arm near disk 7 mm. ; height at the same point6 mm. Mouth-angles so fleshy and puffed as to fill almost entirely the slits ; at the apex appears a small peg-like tooth ; upper teeth wider and spear-head shaped. On removing the thick, flabby skin, the usual large ob- long side mouth-shields are seen, joined their entire length, except without, where they diverge somewhat to give place to the little mouth-shield. The side arm-plates are long, narrow, and curved, and meet fully below, separating the small, irregular, transversely oblong under arm-plates ; at their upper end they . support the tentacle-scales, and unite with the belt of thin scales which repre- sents the upper arm-plate. Disk thick, rising a little above the level of the arms, covered by a very thick, soft skin, which is especially wrinkled over the side mouth-shields. The same skin covers the arms, and is there loose and flabby. Radial shields narrow, rounded, thick and running quite to the cen- tre. No tentacle-scale on first arm-pore ; the next five have one, in form of a small, blunt, thick spine enveloped in a sort of skin bag ; beyond, there are two, the lower of which, towards middle of arm, does not exceed 3 mm., and has a rough, but scarcely clubbed end. Color in alcohol, brownish pink, ap- proaching flesh-color. Station 308, 175 fathoms, 12+- specimens. * The specimen described is not of the same size as the one figured. , 64 P BULLETIN OF THE Ophiocreas caudatus sp. nov. Plate XVI. Figs. 439 - 442. Special Marks. — A large species. _ Arms to disk as 13 to 1. No tentacle- scale on the first arm-joint; then for several joints only one, small and peg- like ; thereafter two, which never grow very long. Skin thick. Description of an Individual (Station 232).— Diameter of disk 22 mm. Length of arm about 300mm. Width of arm close to disk 5.6mm. Height of arm near base 5.5mm. Mouth-angles covered with very thick skin giving a swollen look ; on their sides and above the second mouth-tentacle is a sort of pavement of irregular flattened grains. , Twelve large thick teeth, longer than wide, with cutting edge shaped like a rounded angle ; the two lowest are small- est and are less flattened. Arm-joints obscurely indicated by the arm-bones, whose outlines are seen through the skin. Arms broader above than below ; covered with a thick skin, which, when partly dry, presents under the micro- scope a minutely tuberculous surface. No tentacle-scale on first arm-joint ; be- yond this there is only one, short and peg-like, for some distance, sometimes as far as the thirteenth joint ; after which there are two, still short, and cased in very thick bags of skin ; on last third of arm the scale of the brachial side has become stout, thorny-ended, and much the longer (8 mm.). Disk thick and angular, covered with thick skin similar to that of the arms, and having interbrachial spaces re-enteringly curved. Radial shields high and narrow, diverging from the centre of disk to sides of the arms. The genital openings are long, extending from upper edge of disk to mouth-ring. Color in alcohol, uniform pinkish brown. Station 232, off Enosima, 340 fathoms, 2 specimens. Another somewhat smaller specimen had already two tentacle-scales on the fifth joint. Ophiocreas abyssicola sp. nov. Plate XVII. Figs. 470-473. Special Marks. — Arms scarcely as high as wide, about eight times the diameter of the disk. Skin quite smooth, with radial shields scarcely indicated externally. Genital openings very short, and situated near the inner inter- brachial angle. Description of an Individual (Station 941). — Diameter of disk 7 mm. Length of arm about 60mm. Width of arm close to disk 1.7 mm ; height of same 1.2mm. Four or five short, flat grains above the second mouth-tentacle, on the sides of each mouth-angle. Seven stout, nearly equal teeth, shaped like a blunt spear-head. On removing the skin the small, irregular, rounded mouth-shield, and large, longer than broad side mouth-shields, can be seen ; the latter are often broken. Under arm-plates rather large, rounded, as broad as long, closely soldered, and with vague outlines. Side arm-plates small, MUSEUM OF COMPARATIVE ZOOLOGY. 65 rounded, and swollen, closely joined with the under arm-plates. Arm-joints recognizable through the skin. Arms rounded and slender, tapering very gradually to the end. Disk flat and somewhat angular, not rising above level of arms, covered with soft, moderately thick skin. Radial shields shorter and wider than in other species, separated their entire length, and very thin and flat ; from the outside they are scarcely indicated, and they do not meet in the centre. Two short, stout, bluntly pointed tentacle-scales, the lower one longer, and both nearly naked. Two very short genital openings, about 5 mm. long, near inner angle. When the skin is removed the genital plate and scale are seen, the plate being rounded, much longer than broad, tapering from with- out inward, and having the small, peg-like scale attached near its outer end. Color in alcohol, pale straw. Station 241, 2,300 fathoms, 5 specimens. This species, well distinguished from others, is remarkable for the great depth at which it lives. The genus is usually found not far below the 100- fathom line, and 500 fathoms may be considered deep for it. Ophiocreas cedipus sp. nov. Plate XVI. Figs. 443 - 446. Special Marks.— Arms about twenty times the diameter of disk, and slender, except the base, which is swollen above, and contains the ovaries. Description of an Individual (Station 344). — Diameter of disk 12 mm. Length of arm about 250mm. Arm much swollen for the first four or five joints next disk, where its width is 3.5 mm., then suddenly shrinking to 2mm. with a height of 2mm. There are numerous small, flattened grains extending along the sides’ of the mouth-angles, above the second mouth-tentacle. Eight or nine broad, flat teeth, with well-rounded cutting edge, the two lowest being much narrower and peg-like. On removing the skin the mouth-shield is seen to be very small, a little longer than wide, with ends much rounded. Side mouth-shields very large, much longer than wide, with ends much rounded. Side mouth-shields very large, much longer than wide, somewhat swollen, meeting within where they are narrowest. Under arm-plates composed of two or more small pieces. Side arm-plates swollen, meeting below, and, at the base of the arm, joined to thick, narrow, ridge-like upper arm-plates, which arch upward, and nearly or quite meet on the median line. Disk angular and flat, with re-entering marginal curves. Radial shields narrow and highly arched, not quite meeting in the centre, covered with thin skin, which under the microscope is seen to be set with fine points. Genital openings large and wide, occupying the whole height of the disk. Where the skin is removed the genital plate is seen to be long, very broad and thick, tapering inward ; the genital scale is small and peg-like. At base of arm there is only one tentacle-scale ; beyond, there are two, the upper one very small, and spini- ’ form, the lower one enclosed in a thick club-ended skin-bag. On opening the singular swelling on the upper side of the base of the arm, VOL. VI. —NO. 2. 5 66 BULLETIN OF THE it is found to be a pouch full of large eggs, which are about .7mm. long. In fact, the ovaries are in this species thus pushed beyond the disk, somewhat as in Star-fishes. ‘ Color in alcohol, pinkish or yellowish brown. Station 344, 420 fathoms, 3 specimens. ASTROSCHEMA Lrx. Astroschema horridum sp. nov. Plate XVII. Figs. 458 - 461. Special Marks. — Entire surface covered with little, swollen, oblong angular plates or scales, bearing minute points. | Description of a Specimen (Station 170). — Diameter of disk 12.5 mm. Length of arm 195mm. Width of arm near disk 4.7mm; height of arm 4.2mm. Seven stout, thickened, rather small teeth, of the usual short spear- head shape. The mouth-angles are paved with large, flattened, swollen grains, but have no true papille. Arms nearly cylindrical, very slightly swollen for their first 20 mm., beyond which they taper very regularly. They are evenly and pretty closely beset with minute points, like little blunt spines, about 4 in the length of 1 mm.; these, on allowing the surface to dry, are seen to stand on small, swollen, oblong, angular plates or scales, which may be considered as exaggerated grains set with points. This covering continues quite to the end of the arm, where, however, the grains are more rounded and without points. Disk thick, rising a little above the arms, elegantly scalloped on its margin, with large radial shields (ribs), which are thick, swollen, and projecting at their outer ends, and taper inward to the centre, where they meet ; its surface is paved with little oblong, angular, swollen plates or scales, rather coarser than those of the arms, and bearing similar minute points. Genital openings straight, and occupying about one half the height of the disk. Mouth-tentacles enclosed in a tube of flat grains; the next pair has no tentacle-scale ; the next one and those beyond have two, which are short at first, but about 40 mm. out become somewhat suddenly elongated, the upper one, about 1.3 mm. in length, remaining blunt spiniform, while the lower and larger takes on the form of a cylinder 3 mm. long, with a rough, swollen end. The two lines of pores lie closer together than usual, so that the furrow on the lower side of the arm is narrow. Color in alcohol, pale reddish brown. Station 170, 630 fathoms, 1 specimen. Astroschema salix sp. nov. Plate XVII. Figs. 466 - 469. Special Marks.— Granulation fine, even, and close set; 7 or 8 grains in the length of 1 mm. Disk flat, with ill-distinguished radial shields. At tip of arm the lower tentacle-scale takes the form of a compound hook, MUSEUM OF COMPARATIVE ZOOLOGY. 67 Description of an Individual (Station 170).— Diameter of disk 8.5 mm. Length of arm 85 mm. Width of arm near disk 3 mm. Height of arm 2.4mm. Mouth-angles covered with minute, close, smooth granulation, and bearing at their apex the usual wide spear-head shaped teeth. Arms wide next disk, tapering rapidly for about 15 mm., and thence very gradually to their tips; covered by a fine, even, smooth, close-set granulation, 7 or 8 grains in the length of 1mm. The skin, being thin, allows the outlines of the joints to show through, especially near the ends. Disk flat, scarcely rising above arms, and with a similar granulation, though rather looser on the upper surface. Radial shields scarcely to be distinguished, except at their — outer ends. The first pair of pores outside mouth-slit has no scale; the next six have only one; those beyond two, whereof the inner and larger is cylin- drizal, with a somewhat swollen, rough end, and attains, about two thirds out on arm, a length of 1.8mm. At the tip, the lower scale takes on the form of a flattened compound hook, with four curved teeth on its edge. Color in alcohol, very pale brown. Station 170, 520-630 fathoms, 1 specimen. Astroschema brachiatum sp nov. Plate XVII. Figs. 462-465. Special Marks. — Arms twenty-four times the diameter of the disk, higher than wide, with a smooth, even granulation, 6 to 9 grains in the length of 1 mm. Description of an Individual (Station 33).— Diameter of disk 11 mm. Length of arm 270 mm. Width of arm near disk 3mm. Height of arm at same point 3.8 mm. The granulation of the disk is, as usual, projected over the mouth-angles, but there are no conspicuous grains which simulate mouth- papille. Teeth short, blunt, peg-like spines. Arms long, smooth, higher than wide, cleanly arched, and with only faint joint-ridges; they are closely and uniformly covered with a smooth granulation, 6 to 9 grains in the length of 1 mm. Disk high and arched, with well marked, somewhat elevated radial ribs, running nearly to the centre. The granulation is about as on the arms. Geni- tal openings rather short; their upper ends not reaching the level of the top of the arm. No tentacle-scales (spines) on first pair of pores outside mouth-slit ; the next two pairs have one scale, and those beyond two, of which the lower one attains a maximum length of 2 mm., and hasa rough, slightly clubbed end. Color in alcohol uniform chocolate-brown. Station 33, 435 fathoms, 1 specimen. _ This species stands between A. tenue and A. leve ; its arms are much thicker than those of the former, and much longer than those of the latter. 68 BULLETIN OF THE Astroschema tumidum sp. nov. Plate XVII. Figs. 450 - 453. Special Marks. — Disk and arms covered by regularly spaced, pointed, coni- eal grains. The bases of the arms for two or three joints are strongly swollen. Description of an Individual (Station 192).— Diameter of disk 8 mm. Length of arm 135 mm. Greatest width of arm, close to disk, 3.7 mm. Width, beyond the swelling, 2.3mm. Height of arm, at same point, 1.8 mm. Seven or eight short, flat teeth, with a curved cutting edge ; the lowest one smallest. The general granulation of the disk is continued in a somewhat coarser form over the mouth-angles, and up their sides ; but there are no true mouth-papille. Arms well rounded, without any flattened surface, strongly swollen and ribbed, for the first two or three joints, but even and tapering be- yond ; set with pointed conical grains which are regularly spaced, about 5 in the length of 1 mm., and which rarely touch each other. Disk strongly con- tracted in interbrachial spaces, and occupied chiefly by the high, wide radial shields (or ribs) which run quite to the centre ; granulation somewhat more sparse than on arms. On first arm-pore there is no tentacle ; the next has one, cylindrical, tapering and blunt, with sometimes a second rudimentary one ; the pores beyond have two, whereof the upper one is, as usual, much the smaller. One third out on the arm, the larger scale attains a length of 2 mm., and is rough at the end and slightly clubbed. Color in alcohol, pale yellowish brown, with interbrachial spaces of disk gray. Station 192, 129 fathoms, 1 specimen. This species presents the same swelled base of the arm found in Ophiocreas edipus, and doubtless for the same purpose, an egg-pouch. The genera As- troschema and Ophiocreas though differing widely in their remote members, are, in their proximate species, only distinguished by surface granulation in the former. Astroschems rubrum sp. nov. Plate XVII. Figs. 454-457. Special Marks. — Arms, at bases, not cleanly arched, but somewhat angular. Mouth-angles puffed so as to nearly close the slits. Granulation fine, smooth, and close-set, 6 or 7 in 1 mm. long. Tentacle scales short and scarcely club- ended. | Description of an Individual (Station 310).— Diameter of disk 12 mm. Length of arm 160 mm. Width of arm near disk, 3.5mm. Height of arm 3.5mm. Mouth-angles so swollen as nearly to close the slits, and covered by a smooth granulation much obscured by skin ; at the apex are small wide teeth. Arms near base as high as wide and not cleanly rounded, but inclined to be angular, and showing distinctly the outlines of arm-joints ; tapering uniformly ; near their ends higher than wide; covered by a close-set, smooth, fine granula- tion, which, at bases of arms and on disk, has 6 or 7 grains in the length MUSEUM OF COMPARATIVE ZOOLOGY. 69 ofl mm. Disk thick, but flat on top, and rising but little above arms, covered by a thin skin, which is finely, closely and evenly granulated. The radial shields are faintly indicated by flat ridges running to the centre. Mouth-tenta- cles enclosed in tubes ; the next have no scale; the next three or four have but one ; those beyond, two, which at first are small and spiniform, and are nowhere long, the lower one attaining a maximum length of 1.4 mm. with a cylindrical form, and a rough scarcely swollen end. Color in alcohol, brown- ish red, approaching flesh-color. Station 310, 400 fathoms, 4 specimens on a Gorgonian near Brandella. By its color and smooth surface O. rubrum may easily be mistaken for an Ophiocreas. ASTROCLON * gen. nov. Arms beginning to branch at a considerable distance from the disk, and having but few forks, nearly as in T'richaster. Disk rising well above the arms, and granulated, as are the latter. The tips of the twigs are encircled at each joint by a double belt of hook-bearing grains. Along the under surface of the base of the arm are two longitudinal lines of large, transverse slits, a pair to each joint, from which issue short tentacles; and above these on either side is a row of peg-like tentacle-scales. Mouth-angles naked on their sides, but with a bunch of spine-like papille at the apex. Two very large genital openings in each interbrachial space. Astroclon propugnatorist sp. nov. Plate XVIII. Figs. 481 - 486. Special Marks. — Animal covered above by a closely soldered granulation, in which appear numerous dark patches, which are small, oblong, smooth plates, sometimes raised like tubercles, and sometimes sunken. Toe. the granulation is microscopic, and, on part of the under surface a arm, wanting. Five short, wide, smooth tentacle-scales. Description of an Individual (Station 192).— Diameter of disk 65 mm. Length of arm: from disk to 1st fork, 160 mm. ; from Ist fork to 2d, 36 mm. ; 2d to 3d, 137 mm.; 3d to 4th, 26mm.; 4th to 5th, 16mm. ; 5th to 6th, 16 mm.; 6th to end, 16 mm.; total, 407 mm. Width of arm near disk 14 mm.; height ‘at same point 10mm. Mouth-angles small, and on their sides smooth, eae, * dornp, star; krdv, twig. t Dr. Carpenter has happily translated “Challenger” by mpéuaxos, the Homeric word for a champion who stood in front of the line of battle and challenged the leaders of the enemy. Propugnator is a verbal translation, although it seems usually to signify rather a defender. I am told by high authority, however, that its present use is allowable. Goliath was such a challenging champion, but he is de- scribed in the Vulgate as vir spurius, an expression not applicable here. 70 BULLETIN OF THE at the apex a vertical tuft of small, smooth, short, spine-like papille. From near mouth to margin of disk the arms grow wider, but begin to taper from that point. They are cleanly arched above, but flat on the lower surface, a: large portion of which is occupied by the deep, oblong, transverse pits (the largest 3.5 mm. long) on whose inner side stand the tentacles, so that this surface presents the appearance of a central, narrow, radiating strip, on whose sides are the tentacle-pits, arranged like the feathers of an arrow. This central strip has a very fine granulation, nearly obscured by skin; but the lateral region is quite smooth. The sides and upper surface are covered by a coat of soldered grains, about 2 in the length of 1 mm. Among them appear numerous small, smooth, slightly sunken, rounded, dark plates, usually 1.5 mm. in diameter; these begin near the tip, with a single plate on the upper surface of each joint, and gradually increase in number towards the base of the arm. The terminal twigs are encircled by double belts of hook- bearing grains (Fig. 486), but the intervening spaces are not yet granulated. Disk thick, rising well above arms; covered above by a soldered granulation similar to that of the arm, with scattered smooth plates, which sometimes are raised and sometimes sunken. Interbrachial spaces below covered by a minute granulation, which is more or less obscured by skin, and seems smooth to the naked eye. Radial shields not externally indicated. Genital openings very large, extending from opposite the second tentacle-pit nearly. to margin of disk, and capable of great distention; one of them was open to the width of 9mm. The mouth-tentacles and first pair on the arm have no tentacle-scales ; thence to margin of disk there are two or three, minute and peg-like, to each tentacle ; for some distance beyond the margin each tentacle has five small, thick, short, wide scales, about 1.5 mm. long, arranged in a single line. Color in alcohol, uniform yellowish brown, with chocolate patches where the smooth plates are. Station 192, 129 fathoms, 1 specimen. . The single specimen had lost one arm and a piece of the disk, the result apparently of an injury, and not of self-division. There was sent me recently a single Ophiuran of this Expedition, which has: most singular arm-spines, like round-headed nails, or long-handled parasols. They are arranged, not in one, but in several rows, thus forming an exception to all other genera in the group. There is a similar species, but of quite a differ- ent genus, in the collection of the second “ Blake” Expedition; and I propose to prepare on these a separate paper. MUSEUM OF COMPARATIVE ZOOLOGY. DESCRIPTION OF PLATES. PLATE XI. Fig. 278. Amphiura maxima, below ; 3. Fig. 279. sf $ above ; §. Fig. 280. ne “ tentacle-scales ; 3. Fig. 281. a ‘¢ _ arm-spines ; 3. Fig. 282. “iy bellis, below ; 3. Fig. 283. 7. ‘*.” above > 4. Fig. 284. 4 ‘¢ arm-spines ; 3. Fig. 285. aS incana, below ; 7. Fig. 286. “ radial shields ; 4. Fig. 287. Re “« arm-spines ; 4. Fig. 288. By argentea, below ; &. Fig. 289. Ay ih above ; $. Fig. 290. ty si arm-spines ; &. Fig. 291. ‘¢ _ joints near tip ; ¢. Fig. 292. AF acacia, below ; 4. Fig. 293. a: *¢ above ; 4. Fig. 294. - ‘¢ arm-spines ; 2. Fig. 295. constricta, below ; 4. Fig. 296. af “) -above:s' f. Fig. 297. “ i. arm-spines ; 4. Fig. 298. : ” joints near tip of arm ; 4. Fig. 299. me tomentosa, below ; 3. Fig. 300. eo ri above ; 2. Fig. 301. < i arm-spines ; 3. Fig. 302. a tris, below ; 2. Fig. 303. a *** above; §. Fig. 304. . ** arm-spines ; 4. Fig. 305. = lanceolata, below ; §. Fig. 306. e above ; . Fig. 307. a . arm-spines ; ¢. Fig. 308. = glabra, below ; §. Fig. 309. . “* above; §. Eig. 310. ke ‘* arm-spines ; {. Fig. 311. oe angularis, below ; +. Fig. 312. br = above ; i. Fig. 313. ot: bs arm-spines ; j. Fig. 314. Py dilatata, below ; §. Fig. 315. “ bs above ; §. Fig. 316. i: Ge arm-spines ; 4. = 1 BULLETIN OF THE PLATE XII. 817. Amphiura concolor, below ; {. 318. ss ly above ; 4. 319. oe os arm-spines ; j. 320. es dalea, below ; %. 321. it: “above; 3. 322. ee ‘¢ arm-spines ; 3. 323. es cernua, below ; ¥. 324. Ss above; {. 325. a “© arm-spines ; {. 326. ‘ glauca, below ; 4. 327. 2. ss above; #¢- 328. - ** arm-spines ; 4. 329. * Verrilli, below ; 4. 330. ne “© above; $. 301. se ‘© arm-spines ; {- 332. = canescens, below ; 4. 333. i a above ; {. 304. e 7% arm-spines ; . 335. “ patula, below ; 4. 336. 2 id above ; 3. 337. sg “ — arm-joints ; 4. 338. Amphilepis patens, below ; $. 339. oe ‘above; 3. 340. ‘a « arm-spines ; ¢. 341. Ophiocnida pilosa, below ; }. 342. “above ; 4. 343. nf * — arm-spines ; {. 344. es scabra, below ; 4. 345. i ty above ; {. 346. x ‘© arm-spines ; 4. PLATE XIlil. 347. Ophiactis flexuosa, below ; 4. 348. “ # above ; ¢- 349. ws . “ arm-spines ; f. 350. he nama, below ; 4. 351. “ “above ; 4. 352. sg « arm-spines ; 4. 353. e canotia, below ; ¢. 354. a ‘© above; 4- 355 ef «© arm-spines ; 4. 356. v poa, below ; {. 357. uf “© above; ¢. 358. 7 «© arm-spines ; §. 359. . cuspidata, below ; §- ig. 360. . 361. . 362. g. 363. . 364. . 365. . 366. . 867. . 368. . 369. . 370. . S71. . 372. 5878. . 374. . 875. . 376. . 877. . 378. . 379. . 380. ee . 382. - 383. , 884, . B85. . 386. 387. . 388. . 388 389. . 390. £291. . 392. . 393. . 894. . 895. . 396. . 397. . 398. . 399. . 400. . 401. . 402, . 403. . 404, MUSEUM OF COMPARATIVE ZOULOGY. 73 Ophiactis cuspidata, above ; 3. ee is arm-spines ; 3. “ resiliens, below ; ¢. “ vis above ; j. Si = arm-spines ; i. 2 hirta, below ; §. ee ‘* above; %. bh ‘* arm-spines ; {. Ophiostiyma africanum, below ; 4°. as above ; 42. * _ arm-spines ; +2. Ophiochondrus stelliger, below ; 2. - ee above ; 2. a “ arm-spines ; 4. Ophiopholis japonica, below ; 3. - “ - above ;)-6. Re ‘* arm-joints, profile ; 3. PLATE XIV. Ophioconis pulverulenta, below ; 3. } > Y J Ss 6 co TING SLIOTYPE PRIN HE HE 7 a () a0 Ra A THE HEMOTYPE PRIN oa ee SRINTINGCO. 220 DEVONSHIRE 31 I ) iy y ¢ XV/L GCECE 4 ead! 2 a _ ‘e iat i ieee faa Pah se eee Ss f.. ee = k es 5 | Oe ee dk De - : he 5 i aT ; a ,, Sa wr au iva ’ 7 rn re aa _ pe ae — = we eras — = vee ~ + & u ‘ 5 & r i ; 2 y EAP at . : , ye i a i 7 - ' aol | -,; , ” 7 ry, | < , eng . 5 pp = \ v j ’ ui pel d , i P ' ° “4 i | j a va 7 ; \ : 1 S Pyar : vad . i; ‘ nye ; and P ° nl « fi ’ fs A 4 Trp Perradn Soom OA fon Tr f J So . mld nat. LHE HELIOTYPE PRINTINGCO. 220 DevonsHie Sr. Bosrott Sate XIX By ay rey gage) ik OAS ant RN: ba - e Yn rey Ae, i * pC a e 2 ; ¥ aaa i ay eae ian . a em ams he 3 ah hone Asal . ) i : 4 ’ : ; Hast oan | ‘ | +9; ; a, ° " =) r aoa : > a 1 be Te a * ® > : " » @ 1 5 nd ~ a > : \ ia 4 7 . ad _ - - Wan #. 6 a 3 & i ; pe i D 6 Ge _ = 7 7 5 4 y aoe , Le - ; ; 7 i ; ’ ‘ « ne - ) 4 7 » = 7 ; oth . , Pu . 3 >= we <> . a a : _ - + 7 4 Eee a! 7 - : i \ n Oi] . ’ 7 : - a > ive 7 fe \ TY <> a a i : : & J 2 e —— + ic ii 7 = 1 " a ; : a f, Me 7 id = a 7 F he : ey ae el ‘ i. J i ’ = al P % *& ~ } : a y) . = ‘ 7 ‘ 1 1 f i a. : | ae ‘ a 7 74 = , ¥ > he ’ 4 a L - ; FA ; ‘ ¥ No. 3. — Reports on the Results of Dredging, under the Supervision of ALEXANDER AGassiZ, in the Gulf of Mexico, 1877-78, by the United States Coast Survey Steamer “ Blake,’ LIEUTENANT-CoM- MANDER C. D. SiGsBEE, U. 8S. N., Commanding. (Published by permission of CARLILE P. PaTTErson, Supt. U. 8. Coast Survey.) NG General Conclusions from a Preliminary Examination of the Mollusca, by W. H. Dat. THE collection made by Mr. Agassiz and Lieut.-Com. Sigsbee on board the ‘‘ Blake” contained about five hundred species, from which the Pteropods and some other groups have been excluded, as will be seen by the tables, leaving 462 species to be considered in this paper. Of course the specific determination of all these forms is a task which must necessarily occupy a large amount of time and labor, and if that had been a necessary preliminary to a report of any kind I should have nothing to say on the subject at the present time. Fortunately, how- ever, the generic affiliations can be approximately determined almost at sight, and species may be almost as readily separated from one another by a practiced eye; so that it is not necessary to wait for the comple- tion of the drudgery of researches into the nomenclature of the various specific forms before announcing any general conclusions. Before proceeding to these it is necessary to make a few preliminary statements. I. The observations herein tabulated are not to be taken as exact in every instance. The limits of a species, or the reference to a subordi- nate generic group, is liable to be modified, occasionally, by more mature study. The examination of the collections for 1878-79, made under the supervision of Mr. Agassiz on board the “Blake,” will doubtless add to, and in some instances change, the figures deduced from the col- lections of the previous season; all that is claimed for the conclusions here put forward is, that the general character of them seems already to be sufficiently established by the evidence in hand. VOL. VI. —NO. 3. a 86 BULLETIN OF THE If. The combination of sundry shoaler-water collections, made by Pourtales and Agassiz on the Coast Survey steamers “ Bibb” and ‘‘ Hassler,” with the deep-sea dredgings, has proved of the highest im- portance, by completing the evidence in several cases where the absence of material from shoal water would have rendered a suspension of judg- ment necessary. III. In several cases where the presence of dead shells in the deep- water material was the only evidence of the presence of a shoal-water species there, its living presence has not been taken as proved unless the multiplication of instances and graduation of depths confirmed the supposition. Ifa too great conservatism has been exercised in this way, it is on the side of safety in the generalizations. The names provision- ally adopted in the tables are of a conservative character as regards their limits ; since, in this way, a more just comparison with the lists of authors like D’Orbigny and C. B. Adams is rendered possible ; and this course is also less likely to result in errors of determination due to insufficient study. ' IV. The absence of any tolerably complete catalogue of West Indian mollusks in accessible shape has interfered with carrying the comparisons as far as might have been desired. The best that could be done was ta compare the lists of C. B. Adams’s Jamaican shells and those described in D’Orbigny and Sagra’s Mollusca of Cuba, to eliminate identical species, and to assume that the resulting list bore about such a proportion to the whole litoral molluscan fauna of the West Indies as the “ Blake” dredgings do toward the whole abyssal fauna. Upon this assumption, however, though so convenient for a brief comparison, no very impor- tant conclusions are based. As the shells quoted by the above-men- tioned authors were all (or nearly all) obtained in the limits of the shore fauna, they afforded a better means of comparing that faunal re- gion with the abyssal region than more modern and complete lists like that of the shells of Guadaloupe (Crosse and Fischer), which contains many true deep-water species brought up on fishing-lines or by coral- hunters. The following are the most interesting and important deductions which seem to result from the facts before me. I. The facts, already known, that certain species of mollusks have a very limited vertical range, forming respectively a litoral and an abyssal fauna, are supplemented by the additional hitherto unrecognized fact that a fair proportion (say 20 per cent in the present case) have a verti- cal range which extends from the true litoral region (less than 50 MUSEUM OF COMPARATIVE ZOOLOGY. 87 fathoms) to the depths of the abyssal region (250 to 2,000 fathoms) un- limited by temperatures actually encountered. II. Of the species with great vertical range (from less than 100 to more than 500 fathoms), the smallest part (ten per cent) are of groups which have been regarded as belonging to or characteristic of the shores of cold or boreal areas. The next larger part (twenty per cent) belong to. groups hitherto considered characteristic of shoaler warm or tropical waters, while more than sixty per cent belong to groups not especially characteristic of the litorale of either region. III. Of the species found in the abyssal fauna without regard to their vertical range above it, ten per cent may be termed boreal, thir- teen per cent tropical, and more than seventy-five per cent uncharacter- istic forms. IV. Since the tropical forms belong to the same groups as those char- acteristic of the local litoral mollusk fauna, it is eminently probable that the abyssalregions have local faunz proper to their various portions, and that a universal exclusive abyssal fauna, so far as mollusks are concerned, does not exist. This must be qualified by the admission of the exist- ence in the abysses (as well as on the ltorale) of ubiquitous species- forms ; which, however, do not form a universal abyssal fauna, any more than Mytilus edulis, Saxicava rugosa, and Poronia rubra form a universal litoral fauna. The local nature of different portions of the abyssal fauna is also confirmed by the distinctness of the Challenger mollusks from those of the Blake, but a very small number appearing identical as far as a cursory examination could determine. There can be no doubt that the uniformity of generally low tempera- tures (and consequently of food) affords special facilities for the wide dis- tribution of boreal forms through the abyssal region. But where adjacent shores can (by washing and sinking) afford a different or greater variety of food without too excessive temperatures, local abyssal faunz will prob- ably always be developed, and with characteristics assimilated to those of the litoral fauna of the same part of the earth’s surface. The present collection shows conclusively that a difference in pressure of some 120 atmospheres and in temperature of 41.5 degrees has been sustained by different individuals of the same species without perceptible change in the external appearance of their hard parts or shells. V. The specific characters of many of the strictly abyssal species ap- pear to exhibit a very remarkable degree of variation within supposed specific limits, although it would seem as if the conditions under which they live must be remarkably uniform. This would indicate that the 88 BULLETIN OF THE tendency to variation is less dependent upon changes in the existing environment than has generally been assumed. The total number of litoral species recorded by Adams and D’Orbigny, throwing out those groups, like the Pteropods, not germane to the inquiry, is 580, as compared: with 461 collected by the Blake. The number of genera represented by the former is about 110, while some 98 genera are found in the Blake collection. The 461 species included in the last-mentioned collection comprise 210 which are litoral or do not reach great depths, while 251 are abyssal or ubiquitous. These numbers are of course approximate, and subject to correction, but probably not seriously in error. Out of 48 species, of 44 genera, having great vertical range, 24 have a range of 500 to 750 fathoms; 17 have a range of from 750 to 1,000 fathoms ; and 7 have a range of from 1,000 to 1,555 fathoms. Bearing in mind that the absolute depth of the extreme range may be much greater than this, the astonishing fact is evident that the same species may experience a difference, between two of its stations, of the weight of nearly two miles of sea-water. The possibility of this of course lies in the permeation of the soft parts by the sea-water, thus equalizing the pressure. It is almost certain, however, that individuals from the great depths would die if removed to shoaler water, unless by extremely slow degrees. It is noticeable among the deep-sea forms that the sculpture tends to be slight, the shell thin, pale or colorless, and in the spiral shells there is a tendency to a knobbing or denticulation of the posterior edge of the whorls at the suture. To each of these peculiarities there are, however, conspicuous exceptions. The following tables exhibit in detail the statistics from which the foregoing conclusions have been drawn. MUSEUM OF COMPARATIVE ZOOLOGY, 89 COMPARATIVE TABLE OF THE LITORAL AND ABYSSAL WEST INDIAN AND GULF FAUNA. | ( CONT SO) Or CO DD D’Orb. Vertical range and Blake. of genus in Group or genus, |C-B.Ad. fathoms. eee STE CHES: Oe S| est ———EE —__ SC — | — ——— —_—<—<$<$_$_____ | —______ Species belong- | Range of single Anatinide 1 7 15 640 5 2 2 640 Ancillaria 1 0 Anomia 2 0 Area 15 6 13 | 1568 3 3 310 | 1568 Astyris (Columb. 3 220 805 0 3 220 450 Avicula 3 0 Bulla 17 4 87 | 1568 1 3 100 | 1568 Cadulus 0 6 30 | 1002 0 6 100 | 1002 Calyptreea 1 1 95 | 100 1 0 95 | 100 Cancellaria g 1 54 84 1 0 54 84 Cardita 2 6 1 8) 640 3 3 2 640 Cardium 10 9 30 187 7 2 30 182 Cassis 4 0 Cerithiopsis 20 11 50 | 1002 2 9 100 | 1002 Cerithium 0 Chama 2 1 80 100 1 0 80 100 Chitonide 12 1 128 2 0 i Cistella 0 9 80 805 0 9 30 805 Columbella 16 ‘| (Astyris.) Conus 4 S 19 100 3 0 19 100 Corbula 5 10 4g | s05| 5 5 le 100 640 Crania 0 1 105 116 1? 105 116 Crassatella 0 1 30 2 1 0 Crepidula 2 1 2 539 0 1 Crucibulum 0 1 54 128 i 0 54 128 Cylichna 3 100 | 640 1 2 Cyprea 6 0 Cypricardia 1 Dentalium 3 9 50 , 1568 2 Z 50 | 1002 Dolium 2 Donax 4 Erato 1 Erycina 1 Eudesia 1 100 310 0 1 100 310 Eulima 4 10 100 640 6 4 ‘Fasciolaria 2 3 54 292 2 1 220 292 Fissurellidee a. Puncturella ) ( 2 100 | 640 0 2 100 | 640 b. Glyphis lid | 3 50 | 805 1 2 100 | 805 c. Fissurella 1 13 | 805 0 1 13 | 805 d. Fissurellidea | } 1 100 2 1 0 e. Emarginula 2 3 80 | 640 0 3 100 | 640 Fusus 3 5 15 | 1002 3 = 15>} 1002 Galerus 1 1 2 640 0 1 Gastrochena 2 Gouldia 2 3 13 | 1568 0 3 13..\ 1568 Hipponyx 3 1 229 2 0 1 Leda 2 4 54 | 1568 0 4 54 | 1002 90 BULLETIN OF THE ae Blake. ih aren Species belong- | Range of single Group or genus. C B.Ad. fathoms. mg to the species. No. sp. | No. sp. |} From To Litor. | Abyss. | From To 48 | Leptothyra 2 15 | 1002 i 1 15 | 1002 49 | Lima 6 19 640 3 3 19 287 50 | Limopsis 2 13 | 1568 0 g 30 | 1568 51 | Liotia 1 2 80 220 a x 52 | Lithodomus 4 53 | Litorina 7 54 | Lucinide 15 12 19 805 8 4 19 640 55 | Lutraria 3 56 | Lyonsia 1 2 |» 95.) 1920 1 37 2 1920 57 | Mactra 2 58 | Margarita 6 80 | 1568 0 6 80 | 1568 59 | Marginella 17 13 54 } 1002 8 5 54 | 1002 60 | Mitra 6 4 84 119 4 0 4 61 | Modiola 9 1 220 339 0 a 62 | Modiolaria 2 339 640 0 2 63 | Monodonta 5 1 of 220 1 0 64 | Murex 7 5 54 640 1 4 54 640 65 | Narica 3 66 | Nassa 13 3) 13 640 2 1 13 640 67 | Natica 7 4 14 640 2 g 68 | Newra 10 54 | 1002 5 5 84 229 69 | Nerita 6 ; 70 | Neritina 7 71 | Nucula 3 30 640 0 3 30 640 72 | Nuculocardia if 73 | Odostomia Oe 74 | Oliva 6 1 54 2 1 0 75 | Olivancillaria a 76 | Olivella 6 4 72 805 0 4 127 805 77. | Oniscia 2 78 | Orbicula 1 79 | Ostrea 4 80 | Ovula 2 2 12 80 2 0 81 | Patella if ; 82 | Pecten 4 9 13 805 8 1 13 805 83 | Pectunculus 5 2 54 888 1 1 54 888 84 | Pedicularia 1 100 640 0 ] 100 640 85 | Perna 5 86 | Petricola 2 87 | Phasianella 4 1 287 ? 0 1g 88 | Pholas 6 89 | Pinna 4 90 | Planaxis 3 91 | Platidia 1 ||.2120 || 292 10 1 | 120] 292 92 | Pleurotomaria 2 69 | 200 if 1? Plewurotomide i 93 | a. Bela | bs 3 | 3391 805| 0 3. |) 4988 isge 94 | b. Drillia, etc. 108 15 | 1568 57 51 100 805 95 | Plicatula 1 2 36 54 2 0 96 | Psammobia 4 97 | Purpura 12 . 98 | Pyramidella ik 1 84 |. 100 1 0 99 | Pyrula 2 100 | Ranella 4 MUSEUM OF COMPARATIVE ZOOLOGY. Vertical range of genus in Species belong- 91 Range of single ee | ef | | ———— Ringicula Rissoa Rissoina Rotella Sanguinolaria Scaphander Scalaria Semele Seguenzia Sigaretus Siliquaria Solarium Solecurtus Solen Solenella Sphenia Spondylus Stomatia Strombus Tellinides Terebra ‘Terebratula Terebratulina Teredo Thecidium Tornatella Trichotropis Triforis Tritonium Trivia Trochidee a. Gibbula b. Calliostoma Turbinella Turbo Turbonilla Turritella Typhis Utriculus Veneridz Vermetus Verticordia Vitrinella Volvula Voluta Waldheimia (see Eudesia) Xenophora Yoldia Totals and | Blake C.B.A No. sp. | No. sp. 1 1 10 6 6 5 2 0 1 9 ne 4 2 0 1 3 - 0 2 5 3 3 1 0 1 3 2 1 6 27 13 2 4 0 1 0 1 1 0 2 1 4 0 1 0 2 10 } & 6 3 Te 7 9 10 5 2 4 0 3 0 1 18 17 3 6 1 5 0 3 0 1 1 1 2 0 3 | 580 | 462 fathoms. From To 339 640 100 640 54 220 15 805 30 U7 292 2 84 2 80 805 80 805 118 2 13 860 14 640 100 300 30 805 100 111 805 84 2 80 175 100 2 80 805 54 805 37 805 50 640 14 640 127%.) 1002 100 450 30 805 37 805 84 310 640 805 100 2 36 229 182 | 1568 ing to the Litor. | Abyss. 0 1 3 3 0 1 4 3 2 0 0 1 1 0 1 1 0 3 1 0 5 8 3 1 0 1 0 1 0 2 0 4 1 0 1 1 1 0 i 5 0 3 0 9 3 2 2 2 0 3 0 1 14 3 3 3 2 3 0 3 1 0 1? 1 0 3 211 251 species. From To 339 640 #2 805 ? 80 805 80 805 30 805 100 300 30 805 TEL 805 80 805 54 805 70 805 127 | 1002 100 450 84 287 37 805 100 310 36 229 182 | 1568 BULLETIN OF THE te) bo Illustrations of the Range of individual species in Depth. (x, boreal forms ; 0, tropical forms ; n, uncharacteristic forms.) o Arca, 100, 220, 310, 450, 480 fms. o ““ (another sp.) 310, 1568 fms. n Bulla, 100, 450, 533, 568, 640, 805, 1568 fms. ‘Cadulus, 100, 31, 805, 1002 fms. Cerithiopsis, 100, 640, 805, 1002 fms. n 4 (another sp.) 50, 85, 94, 100, 450, 805 fms. n Cistella, 30, 43, 80, 100, 101, 200, 220, 250, 450, 640, 805 fms. » Corbula, 100, 640 fms. =) “ (another sp.) 48, 72, 100; 127, 450, 805 fms. n Dentalium, 50, 80, 84, 100, 101, 119, 175, 200, 539, 640, 888, 1002 fms. = 38 n $ (another sp.) 339, 539, 640, 805, 860, 1568 fms. n Eudesia, 110, 119, 125, 175, 200, 229, 310 fms. Fissurellide. x Puncturella, 100, 220, 640 fms. nm Glyphis, 100, 287, 805 fms. n Fissurella, 13, 50, 80, 72, 127, 640, 805 fms. n Emarginula, 100, 287, 292, 310, 640 fms. nm Fusus, 15, 54, 125, 128, 152, 229, 1002 fms. n Gouldia, 13, 84, 310, 1568 fms. n Leda, 54, 75, 80, 100, 190, 220, 287, 310, 640, 1002 fms. a Limopsis, 30, 84, 100, 119, 220, 292, 310, 447, 450, 480, 539, 640, 805, 1568 fms. m Lucina, 19, 84, 640 fms. x Margarita, 100, 177, 220, 287, 331, 450, 539, 640, 805, 860, 888 fms. x ée (another sp.) 80, 119, 310, 1568 fms. o Marginella, 54, 70, 72, 80, 100, 111, 125, 152, 229, 640, 805, 1002 fms. o Murex, 54, 640 fms. n Nassa, 13, 72, 80, 100, 177, 640 fms. n Neera, 84, 152, 229 fms. n Nucula, 30, 84, 100, 158, 182, 220, 310, 539, 640 fms. o Olivella, 127, 177, 805 fms. n Pecten, 13, 30, 100, 119, 127, 229, 243, 287, 292, 310, 381, 424, 450, 480, 539, 640, 804, 805 fms. m Pectunculus, 54, 68, 80, 84, 95, 119, 888 fms. nm Pedicularia, 100, 450, 640 fms., on Gorgoniz and corals, Pleurotomde. xz Bela, 413, 447, 640, 805 fms. o Candelabrum, 100, 640, 805 fms. o Ringicula, 339, 447, 640 fms. MUSEUM OF COMPARATIVE ZOOLOGY. 93 o Siliquaria, 80, 100, 127, 220, 450, 805 fms. o Solariide, (sp.) 101, 119, 128, 292 fms. 0 : (another sp.) 80 - 805 fms. n Tellina, 30, 54, 72, 80, 84, 111, 229, 805 fms. n Terebratula, 100, 101, 119, 175, 270, 292 fms. n Terebratulina, 30, 80, 100, 101, 115, 119, 127, 220, 240, 270, 292, 450, 471, 539, 640, 805 fms. nm Fornatella, 111, 310, 450, 805 fms. o Trivia, 100, 119, 287, 640 fms. o “ (another sp.) 80, 175, 805 fms. o “ (another sp.) 80, 177, 640, 805 fms. Trochide. n Gibbula, 54, 80, 100, 220, 805 fms. n Calliostoma, 70, 80, 100, 128, 805 fms. o Typhis, 127, 158, 182, 175, 1002 fms. nm Utriculus, 100, 220, 450 fms. n Vermetus, 37, 80, 95, 100, 805 fms. x Yoldia, 182, 190, 450, 805, 1568 fms. Ten distinctively tropical genera with fourteen species. Five distinctively arctic genera with six species. Twenty-eight uncharacteristic (or generally temperate-region) genera with thirty-one species. Total species ranging from litoral to abyssal fauna, and which may be con- fidently quoted, fifty-one, of forty-three genera, FEBRUARY 5, 1880. Hey ane ed oe ea Ted Mera oe ve Oe bhai , A 1/0 MORN eee i 7 sree! i eT din! ACU 1) ae ls, i RUT een y hs a) hea) gt v eV ee Ane Pe Ma ae wh t 2) ap i es eee ee 3 a foe OE Oa Se | PT tA elie nh ys. ie reat | ETN COP BNE OE ORE. oe ae: it 1 ly ¥ . ] ‘ ae 7 ee | i rs! Me lh Peo aut tne ay ne ee wee nara” a, aa, a en ad st Me be a vi 45, /' ‘ * , _ ; ‘ 5 Ah a pe ets Pe ES" iene aa Per an or ie ae fe ene chert SSID ion ys | ts yi eee ein “it it ae CT Se ee Oe Le sia agi dow eng pe gi ia eanae ‘ st 2 le ee pee Aa hed eortiet ope Pips as ai yates CeoneePRCRNE is) ani ee) ik bts a bh ‘oh i 29 les it Siac Feat ait, nk sahil Hels mast at he inal 7 1 3 ‘ ' ; ‘ f ii i é A we . ) F \ = lea th . ab @ ‘OF fy) i om | rr vw 7 ‘Me i ’ > and = . 3 Lae ~ a t u Con . > ; 5 j hl at a * c * i r ‘ ~ in : in j + f te 4 y) : 4 i a e ; ) ‘ f ‘ \ ; i = . ‘ = ‘ ’ > A ‘ ‘ i 7 . % : ‘ I. ; ae —s . ‘ ~ fi 4 4 t ; i , ' > ‘ » U ‘ ¥ Do ni La F \ ai a 1 \ — q : een ‘ 7 iG 3 # ‘ 1 i ‘4 - % ‘ r : : at f ' ‘ t 7 ‘ . 7 + ) ” , i cy! ye re No. 4.—Reports on the Results of Dredging, wnder the Supervision of ALEXANDER AGASSIZ, in the Caribbean Sea, 1878-79, by the United States Coast Survey Steamer “ Blake,” COMMANDER J. R. BARTLETT, U.S. N., Commanding. (Published by permission of CARLILE P. PATTERSON, Supt. U. S. Coast and Geodetic Survey.) VI. Report on the Corals and Antipatharia, by L. F. Pourtaks. CORALS. ALTHOUGH very rich in the number of specimens, the collections made by Mr. Agassiz in the dredging season of 1878-79 have added but few new species. Considering the extent of the ground covered (see Bull. Mus. Comp. Zodl., Vol. VI. No. 1), we may assume that but little will be added hereafter to our knowledge of the association of corals forming the West Indian deep-sea fauna. No other region of the ocean-bottom has yielded so abundant a harvest, and we have therefore no sufficiently complete data for comparisons with regard to geographical distribution. But for the bathymetrical distribution, and its bearing on the deter- mination of the probable depth in which strata of former ages, contain- ing corals, were deposited, the material brought together in the series of papers of which this forms the last * will no doubt prove of some importance. The following table is a recapitulation of all the species described, * Deep-Sea Corals, by L. F. de Pourtalés, Illust. Cat. Mus. Comp. Zodl., No. IV. Zodlog. Results of the Hassler Exped., by A. Agassiz and L. F. de Pourtalés, Ibid., No. VIII. Part 1. Report on the Dredging Oper. of the U. 8. C.S. St. ‘‘ Blake,” by A. Agassiz, L. F. de Pourtalés, and T. Lyman, Bull. Mus. Comp. Zodl., Vol. V. No. 9. : . Compare also, for deep-sea corals of the West Indies, G. Lindstrom, Contributions to the Actinology of the Atlantic Ocean, Kongl. Svensk. Vetensk. Handl., B. XIV. No. 6; and H. N. Moseley, Preliminary Report on the True Corals dredged by H. M.S. “ Challenger,” &e., Proc. R. S., No. 170, 1875. Of Mr. Moseley’s final report I have seen, at the time of writing this, only advance copies of the plates, for which, and for valuable communications, I am indebted to the author. VOL. VI. — NO. 4 8 96 BULLETIN OF THE with their range in depth, and comparisons with other seas, and European and West Indian fossil faunze : — aaa aay SA8 Es eSed | 6a.2 soo # Range in | S$.2 S48 Bey eg Depth. 0 om SES | aaa Se 4 | BESS | oeaZ Pons | ae,5> | 8,85 no a) sfonde ae ae Fathoms. Caryophyllia berteriana . 56-442 1 antillarum . 82-994 af cornuformis 209-450 iL : x : communis . 127-892 iis Biuleeerc tae or maculata 30-88 a polygona 860 Stenocyathus ver miformis 191-460 Thecocyathus cylindraceus . 84-315 che levigatus 100-315 co recurvatus 175 Trochocyathus Rawsonii 82-805 is coronatus 333-861 Deltocyathus italicus 60-888 Ls 1 Stephanocyathus elegans 209-288 - ¢ variabilis . 476 ih $e 1 Leptocyathus Stimpsonii 60-450 1 Paracyathus DeFilippii . 36-805 ae ae laxus 92-164 hy OSes ve 100 Turbinolia corbicula 100-220 Stephanotrochus diadema 734-1200 Schizocyathus fissilis . 56-450 1 Ceratotrochus typus . 250-400 his 1 1 Flabellum Moseleyi . . 118-476 1 ob angulare . é 888 Desmophyllum erista-galli . 309-805 1 *x Cailleti 73-1131 " Riisei 88-120 “ solidum . 315 - x Rhizotrochus fragilis . 84-119 se tulips. 2 84-175 Lophohelia prolifera 195-874 1 1 exigua 36-287 Amphihelia oculata 158-892 1 ay Madracis asperula 36-180 Axohelia mirabilis : 56-287 Lophosmilia rotundifolia 42-163 Dasmosmilia variegata 60-164 ie Lymani. 70-147 Montlivaultia poculum Antillia explanata 75 Bis 1 Parasmilia fecunda 68-450 by De 1 Asterosmilia prolifera 45-94 ame, 1 Solenosmilia variabilis 120-805 1 Cylicia inflata 100-242 * Duncan has 35 species of simple and probably deep-sea corals from all the West Indian forma- tions. x signifies different but closely allied species. MUSEUM OF COMPARATIVE ZOOLOGY. 97 sae | Sse | 823 eva, esd. ELm Range in Sat ema aac ; Species. Depth. > 3m i B a = ; iz S sPod | Bed | SPE S aS & $ Seng | aS oe a 9 on Perce d (ee Bo ee LS Fathoms. Colangia simplex’. 4. |. ‘2 3 . ss | 80-100 _Balanophyllia floridana,. . =. ... « | 26-100 |. . -J|. .. x ; of palilerd ~. « « + «=, » | 36-458 Thecopsammia socialis . . . . . . | 195-262]. 1 ca tintinnabulum . . . . | 120-539 Trochopsammia infundibulum. . . . | 291-805 Dendrophyllia Goést ~ .° . . | $250=400 x altertiatay | s shie oes) | 250-189 ms Gyvarmaides 2. sls 270 a Pormmcopiae =! 5h TOROS Ten Oy ao, 8s x Stereopsammia rostrata. . . . . « | 164-805 aid profunda .. . . . | 539-805 Mataypeusesymmetrica . . . . . . | 116-805 |. 1 PRRREMINR S Oe0% st aah > yyyer| PLG=189 |... ¢] MI sw pa mm ny eo, h LLG HEBD eemerammureta St. et 10088570 (59 1 Duneania barbadensis . . . . . «| 103-191 Haplophyllia paraloxa . . 1.1... 324 Anthemiphyllia patera . . . . . . | 250-400 Total, — 64 species The .total of sixty-four species is nearly as large as the total of the shoal-water or reef corals of the same region, if we reduce the number of the latter, as given by Duchassaing and Michelotti, to its proper proportions by the rejection of merely nominal species. The proportion of simple forms to compound ones is very large, — fifty of the former to fourteen of the latter. The compound ones belong mostly to the families of Oculinidie, Stylophoridee, and Kupsam- mide, with one species each from the Eusmiline and Astrangiacee. Comparing this association with the one prevailing in the same seas in shoal or moderately deep water, we find that there is not a single Species in common to both, and that they are separated by an almost barren narrow zone. We find also that there is not a single simple species in the shoal-water fauna, and that the compound forms belong to the families of Astreide, Oculinide, Fungidee, and Madreporide, the former preponderating by far. There are no Eupsammide. The nearest approaches between the two horizons would be as follows: Madrepora cervicornis dredged living by myself in Barbados in 17 fathoms, Orbicella cavernosa in 15 fathoms in Florida, and Mycediwm fragile in 43 fathoms. The latter species comes in contact with the 98 BULLETIN OF THE following deep-sea forms: Paracyathus DeFilippii, Caryophyllia maculata, Lophohelia exigua, Madracis asperula, Lophosmilia rotundi- Folia, Asterosmilia prolifera, Balanophyllia floridana and palifera, of which the upper limit is between 30 and 40 fathoms. For other seas the case would be somewhat different. In the Pacific and Indian Oceans, for instance, simple corals, as Flabellum and some other Turbinolide, some Balanophylliz, and numerous large Fungie, occupy the shoal or moderately shoal water region, and the prevailing families are different also. Nevertheless, the West Indian bathymetrical distribution seems to offer a fair criterion for the approximate determination of the depth at which some of the strata not lower than the cretaceous have been deposited. In older formations the forms are too different for com- parison. We can thus safely say that some of the miocene, pliocene, and pleistocene strata of Messina, of which the fossils have been so carefully described by Seguenza, were deposited in a depth averaging 450 fathoms, and ranging from abont 200 to 700 fathoms. This average is deduced from the eight principal species. Two species of Eupsammide would however give considerably less. The species identical, or very nearly related, used for this result, are given in the table; some of them still inhabit the Mediterranean, but others have been found living only in the West Indian deep-sea. Some of the miocene beds of the vicinity of Turin are also deep-sea deposits. In the neighborhood of Vienna it is easy to see by means of Reuss’s excellent monographs that great fluctuations of depth have taken place between the deposition of the different strata. The tables appended to Reuss’s Memoir on the Austro-Hungarian Miocene show very well that the beds called “ Oberer Tegel,” for instance, in which there are Astreeans in abundance allied with Porites, are shoal-water deposits; and that the strata called ‘‘ Badener Tegel,” particularly at Ruditz, were formed on the bottom of deep water, the corals found in them being chiefly Turbinolidee, Oculinidee, and Eupsammide. With regard to the West Indian tertiaries, and more particularly the miocene beds, a careful discrimination of the corals of the different strata, such as we have in the papers of Reuss and Seguenza, seems to be still wanting. Reef corals and solitary species are quoted as from the same localities in Prof. Duncan’s papers, and in a fine collection from San Domingo, presented to the Museum by the late W. M. Gabb. In the latter the different matrix in which some of the specimens are — MUSEUM OF COMPARATIVE ZOOLOGY. 99 imbedded points directly to different beds. Prof. Duncan’s statement, that on some islands, such as Antigua and Trinidad, only reef species are found, shows also pretty conclusively that, in other places there must be deep-sea deposits which were not brought to light here. It is rather puzzling to find the West Indian miocene solitary species so different from the living ones. Even when belonging to the same genera (see table) the species of the miocene are of a very massive type, very different from the living; such are the Antilliz and Asterosmilia, with one exception. It is possible that these massive forms, of which we have no analogous examples at the present time, may have been living in the shoal-water, protected by reefs in the same way as the Fungi, or some of the unattached compound corals, as Manicina or Isophyllia. The effect of slow changes of level has to be considered also as a possible cause of mixture of the dead of one level with the living of another. | Caryophyllia berteriana Duca. Caryophyllia formosa Pourt. The more the number of specimens of these forms accumulate, the greater the difficulty to separate them. The principal difference consists in the form - of the septa, very exsert in C. berteriana, very little so in C. formosa, but 1 now find many intermediate forms. The number of the pali, 12 to 16, cannot well be retained as of specific value. Duchassaing has described as new C. sinuosa, corona, and protet, but the descriptions either apply to young specimens or to mere varieties of the older described species. There is in the collection a specimen taken in the act of swallowing a small fish, which is partly inside the mouth, with the buccal membrane stretched from both sides over its middle. Range * from 56 to 442 fathoms, in 19 stations, off Santa Cruz, Montserrat, Guadeloupe, Dominica, Martinique, St. Vincent, the Grenadines, Grenada, and Barbados. Caryophyllia cornuformis Pourt. Old specimens show considerable anomaly in the arrangement of the pali, which are wanting sometimes in nearly one half of the calicle, and their place filled up by enlarged ribbons of the columella. A case of involuntary parasitism, like the one mentioned in ‘“ Deep-Sea * The range in depth in this and the following descriptions refers only to this year’s work. 100 BULLETIN OF THE Corals,” was found in this collection. The coral fastened among the pebbles with which a Phorus has ornamented his shell appears to have flourished remarkably well in that position, as indeed it ought to, having been carried about in search of food, and prevented from sinking in the mud. Range from 200 to 400 fathoms, off Havana and Barbados, Caryophyllia antillarum Povrrt. Range from 82 to 994 fathoms, in 11 stations, off Nuevitas Cuba, Mont- serrat, Guadeloupe, Grenadines, Grenada, and Barbados. Caryophyllia communis Mos., var. costata. Ceratocyathus zancleus Src. Plate I. Figs. 12 and 13. T agree with Dr. Duncan and Mr. Moseley in joining the genus Ceratocyathus* of Seguenza to Caryophyllia. The numerous species described by that author pass gradually into each other. At one end of the series we have the forms with nearly equal septa and costz, like C. communis; at the other those which have them very unequal, like C. zancleus. All our specimens are extreme forms, still more marked in the inequality of septa and coste than the last mentioned. As Seguenza has a Caryophyllia zanclea as well as a Curaioeae zancleus, that name could not well be retained without confusion ; Ceratocyathus costatus, however, is the same. | A series of fine specimens shows the mode of growth. The young are erect, with a thin peduncle attached toa small pebble or shell ; as it grows in height, the support not being sufficient, it falls over on its broadest side, and the ten- dency to grow upward, and to keep the calicle above the mud, produces the curved base. The curvature of those corals which have it in the plane of the smaller diameter is thus easily explained. It is more difficult to understand the curvature in the plane of the greater axis, which is the rule in some species of corals. The largest specimen measures 36 mm. on the greater diameter of the ealicle, and 31 on the smaller. None of our specimens have more than 16 pali; the number can rise to 24, according to Seguenza and Moseley. Some of the young specimens are still straight, and resemble very much Moseley’s Acanthocyathus spinicarens. Range from 127 to 892 fathoms, in 13 stations, off Santa Cruz, Saba Bank, St. Kitts, Guadeloupe, Dominica, Martinique, St. Vincent, the Grenadines, Grenada, and Barbados. * See under the head of Asterosmilia, in ‘‘ Deep-Sea Corals,” a rectification of my remarks on this genus. . MUSEUM OF COMPARATIVE ZOOLOGY. 101 Caryophyllia maculata Mos. Bathycyathus maculatus Pourt. Mr. Moseley has, I think, rightly placed Bathycyathus in the genus Caryophyllia. In 88 fathoms, off Montserrat. Stenocyathus vermiformis Povrt. Plate I. Figs. 15, 16. - Icannot find in my specimens the dissepiments mentioned by Mr. Lind- strém. His figures represent sections near the centre and near the exterior wall, where there are connecting bands ; but I have always found the central part of the chambers unobstructed from end to end. In Pl. I. Fig. 15, I have given a figure of a decalcified specimen, showing the complete cast of the inside cavity ; the outside is entirely uninterrupted by any dissepiments, and shows only the regular little knobs formed by the contents of the small cavities in the wall. In Fig. 16 twoof the segments are separated so as to show the bands connecting them between the pali and the septa. , Range from 191 to 400 fathoms, in two stations, off Havana and Martinique. Thecocyathus cylindraceus Povurt. Range from 84 to 250 fathoms, in three stations, off Havana and Barbados. Trochocyathus Rawsonii Povurrt. Specimens fixed by a rather large base are the most common form, free individuals being comparatively rare. When fixed, there is not much difference from the genus Paracyathus, unless it is the more regular pali. _ Range from 82 to 221 fathoms, in four stations, off Grenada and Barbados. Trochocyathus coronatus Pourt. Odontocyathus coronatus Mos. Very fine specimens, both living and dead, were obtained, but no young ones. Range from 333 to 861 fathoms, in four stations, off Virgin Gorda, Dominica, and Grenada. Deltocyathus italicus Epw. & H. Plate I. Figs. 1-8. I have adopted the name of the original fossil species for the exceedingly variable living forms, as Prof. Duncan has done before, the differences between the living and the fossil being less than between the different living varieties. The living attain a larger size than the fossil forms. 102 BULLETIN OF THE About two hundred and fifty specimens of the different varieties of this species were obtained, so that from the various expeditions we must have about a thousand specimens. Among that number I have not found a single one attached, or showing marks of adherence. There are four well-marked forms, more or less connected by intermediate ones, thongh, on the whole, specimens showing the passage from one form to another are rare, and one form generally prevails in each particular dredging. Variety o, Agassiz. Pl. I. Fig. 2. The typical form on which I based my first description, equicostate, with more or less conical base, costz rather prominent, sharp, finely serrate and granulate. (Deep-Sea Corals, Pl. IL Figs. 1, 2, 3. Lindstrém, Contr. to Actinol. of Atl. Oc., Pl. II. Figs. 15, 16, 17. Moseley,. Madrep.-of the Challenger Exped., Pl. II. Figs. 2 and 3.) This form approaches nearest D. rtalicus ; there are specimens in which the spines of the cost are large and blunt, and resemble the bead-like grains of the fossil species. (PL I. Fig. 3.) This was considered by Reuss and by myself as the chief specific difference between the fossil and living forms. The variety australiensis, Duncan, does not differ particularly from this one; but D. orientalis, Duncan, is different. The corals referred to this genus by Mr. Tenison-Woods do not appear to me to belong here, as far as the very rough figures allow me to judge. Variety B. PI. I. Fig. 4. Like the preceding in most particulars, but more hemispherical in outline ; the cost are a little more differentiated, and the primaries have sometimes a slight enlargement or blunt knob in the middle of their length, showing a tendency at one period of their growth to form the points characteristic of the next form, or variety calcar. The pali in this form are not very prominent, and the junction of the septa of younger with those of older cycles occurs far down towards the centre of the calicle. Some specimens resemble very much Trochocyathus obesus, one specimen of which from Tortone, Italy, in the Muse- um collection, has likewise only one knob or blunt spine on the primary costee. Variety y, calcar. Pl. I. Fig. 5. (Deep-Sea Corals, Pl. II. Figs. 4 and 5, and Pl. V. Figs. 9 and 10; and Hassler Exp., Pl. VI. Fig. 11. Lindstrém, 1. c., Pl. I. Fig. 13, Pl. II. Figs. 14, 18,19.) I give the figure (Pl. I. Fig. 1) of the specimen, which has induced me to consider this only a variety of the other form. Besides the specimen with double horns figured in Deep-Sea Corals (Pl. V. Fig. 9), there is another one in the present set with three or four horns on the primary cost, appar- ently the result of an injury. Reuss mentions a specimen of D. italicus with remarkably thickened, and almost lamelliform, primary and secondary septa, so that it seems that the fossil form had also the tendency to vary in the same manner. . MUSEUM OF CQMPARATIVE ZOOLOGY. 103 Variety 6.—PL. I. Figs. 6, 7, 8. Base nearly flat, with a sinall umbo in the centre, hardly marked in most specimens, outline of section somewhat re-entering above, so that the diameter of the calicle is somewhat less than the diameter of the base. Coste equal, flat, thick, and contiguous, separated only by a linear though rather deep furrow, finely granulated, and having a faint granular keel. The pali are thick, and the columella oblong, composed of thick pillars, and well separated from the pali; the septa are thickened at the outer borders, covered laterally by short thick spines. All the specimens are uniformly white, without pur- plish spots. Moseley’s D. magnificus resembles it in outline, but has not the same costee, septa, and columella. JI have seen no passages between this form and the others, when adult, but in the young the coste are thin, and not essentially different from variety a. Depth seems to have no influence on the prevalence of one or the other form. In the polyps the outer sphincter when contracted covers the tentacles which are drawn back in the notch between the septa and pali. The office of the pali seems to be partly to support the buccal membrane, partly to protect the retracted tentacle. They never support extra tentacles in any of the corals in which I have had the chance to observe the well-preserved polyp. Range from 73 to 878 fathoms in 39 stations, off Havana, in Old Bahama Channel, off Santa Cruz, Virgin Gorda, St. Kitts, Montserrat, Guadeloupe, Dominica, Martinique, St. Lucia, St. Vincent, the Grenadines, Grenada, and Barbados. Stephanocyathus elegans Srcuenza. Three fine specimens of this species were obtained, two living and one dead. They agree most with Seguenza’s variety subspinosus. The second lobe of the pali, generic character according to Seguenza, resem- bles the parts of the columella, but is well separated from it ; it is not constant, and distinct only in the second or third order. The columella, which is formed of twelve or more blunt prongs, is in younger specimens more diffuse. The septa of the fourth cycle unite through their pali with those of the third, and the latter with the second. The septa of the fifth cycle are small, and reach only half-way to the centre. The polyp has stout tentacles; in one specimen those of the three first eycles were white, the others dark purple, with white tips; in the other they were all purple, those of the youngest order least so. They are disposed in several circles, and do not appear to be very retractile. The outer sphincter is not distinctly marked. The buccal membrane is very thin, and in both speci- mens many of the pali had pierced it. Range from 209 to 288 fathoms, in three stations off Barbados, 104 BULLETIN OF THE Stephanocyathus variabilis Srecurnza. Plate II. Fig. 2. Two specimens, one living and one dead, are referred to this species. They are both larger than those figured by Seguenza, and differ slightly from his description. There is no plicated rudimentary epitheca, and the costee remain very flat and indistinct to the edge of the calicle, instead of becoming ata 8 nent and cristiform. Otherwise there are no essential differences. The polyp seems to have been rather highly colored, dark purplish in alcohol in all its parts except the larger tentacles, which are whitish. Ten- tacles stout, forming a double circle at a considerable distance from the mouth. Buccal disk radially plicated, and very tough. Diameter of largest specimen, 48 mm. Height, exclusive of primary and secondary septa, 8 mm. Height of primary septa, 5 mm. In 476 fathoms, off Martinique. Leptocyathus Stimpsonii Poort. Both the long and the short varieties. Range from 92 to 400 fathoms, in two stations, off Havana and Genial Stephanotrochus diadema Mose ey. Plate Il. Fig. 1. One living and two dead specimens. The tentacles were remarkably full of nematocysts, and must have been quite long. Those of the three first orders are not very different from each other in size, and about equidistant from the centre; those of the fourth and fifth are smaller and farther removed. The tentacular circle is quite distant from the mouth, having a large bare plicated buccal disk. In 734 fathoms off Guadeloupe, and 1,200 fathoms in lat. 19° 7' N., and long. 74° 52’ W. . Schizocyathus fissilis Pourr. Range from 56 to 170 fathoms, in seven stations, off Martinique, St. Lucia, Grenada, and Barbadoes. Paracyathus laxus n. sp. Plate I. Figs. 9-11. Corallum turbinate, turgid, short-pedicellate, sometimes becoming free when attached to a small object, which then becomes covered up by an epithecal growth. Generally dark-colored. Costze not prominent, finely granulated, and separated by a fine linear convex ridge. They are covered by a very thin rudimentary epitheca, through which the granulations can be seen. MUSEUM OF COMPARATIVE ZOOLOGY. 105 The calicle is circular, with a moderately deep fossa. The septa are somewhat exsert, thin, rounded, with granules on the sides, arranged in rows parallel to the edge. Four cycles and part of the fifth in most of the systems, which are thus stulercbat unequal. Pali prominent and large, rather irregular, sometimes two or three lobed ; columella much looser than in the other West India species. The young have a very loose structure, with thin lamellar pali, and rudimentary columella not yet developed into pillars. ‘ Largest specimens, 30 mm. high ; diameter of calicle, 19 mm. Range from 88 to 164 fathoms, in four stations, off Montserrat, Martinique, and Grenada. Paracyathus DeFilippii Ducu. & Micn. Very variable species, which may in the end be found identical with the Mediterranean species, P. striatus and pulchellus. I have had no opportunity for direct comparison. : ' ‘Range from 56 to 458 fathoms, in sixteen stations, off Santa Cruz, St. Kitts, Montserrat, Dominica, Grenada, Bequia, and Barbados. Ceratotrochus typus Povrr. Conotrochus typus SEG. Ceratotrochus hispidus Pourt. “A few more specimens obtained make it evident that the two corals above named are the same. I have before me specimens entirely or partially covered by. an epitheca, or completely destitute ofit. The last I have called Ceratotrochus hispidus. The genus Conotrochus of Seguenza, also adopted by Reuss and Duncan, must necessarily be dropped, since it differs from Ceratotrochus only by the presence of an epitheca. Ceratotrochus multispinosus has, according to M.-Edwards and Haime, a partial epitheca; and, looking over a series of speci- mens from the Italian tertiary, I find that the character is just as variable, the epitheca being total, partial, or absent. It is rather unfortunate to have to retain Seguenza’s specific name for a species not very typical in its characters. Range from 250 to 400 fathoms, in two stations, off Havana and St. Kitts. Flabellum Moseleyi Pourr. Plate II. Figs. 13 and 14. Corallum with a rather long and slender peduncle, strongly curved in the plane of the smaller diameter; a scar of attachment at the end. Calicle widely open, elliptical, diameters as 1 to 1.3. Margin horizontal. Coste of the first and second order about equal, forming stout more or less knotty ridges ; the lateral ones not very different from the others, except in the younger stages, where they are cristiform. The other costz are represented 106 BULLETIN OF THE by mere shallow furrows. Angle of aperture abont 40°. The whole surface is marked with chevron-shaped lines of growth; in one specimen the whole surface is finely granulated, in the others it is smooth and shiny, as usual in the genus. The septa are in six systems and five complete cycles. They are marked with fine radiating granulated ridges. The primaries and secondaries are about equal, and very exsert; all the others remain below the border of the calicle, which is deeply indented. There is a callous thickening at the base of the septa, in the bottom of the fossa. The color of the corallum is a dirty flesh-color, inside and out. The tentacles are equal in number to the septa; I _ do not find the small supernumerary ones noticed by Moseley in Fl. alabastrumi There appears to be no outer sphincter to cover them. The diameters of the largest specimen are 5 and 4 cm. It is somewhat related to Moseley’s Fl. alabastrum, but differs from it by its elliptical outline, long and curved peduncle, and horizontal margin. Five fine living specimens were obtained. Range from 118 to 476 fathoms, in six stations, off Dominica, Martinique, Grenada, and Barbados. 1 Desmophyllum Riisei Ducn. & Mics. Thalamophyllia Riisei Ducu. Plate I. Fig. 14. This is a true Desmophyllum, differing from the typical ones in growing always in clusters from an incrusting base. It is hardly necessary to form a new genus for it on that account. I can find no dissepiments, as stated by Duchassaing. The corallites are much longer and narrower than in the figure of Du- chassaing and Michelotti. They are generally 2 or 3 cm. high, with a diameter of only 5 to 7 mm. Range from 88 to 120 fathoms, in five stations, off Montserrat, Deiminiios ae Martinique. Desmopbhyllum crista-galli Epw. & H. In 399 and 442 fathoms, off Martinique and Barbados. Desmophyllum Cailleti Ducu. & Micu. é Range from 73 to 1,131 fathoms, in eighteen stations, off Havana, Nuevitas Montserrat, Guadeloupe, Dominica, St. Lucia, St. Vincent, and Barbados. Rhizotrochus tulipa Poort. Range from 84 to 106 fathoms, in three stations, off Barbados. MUSEUM OF COMPARATIVE ZOOLOGY. 107 Lophohelia prolifera Epw. & H. A variety with strongly marked primary and secondary costz. ; In 291 fathoms off Grenada, and in 874 fathoms in lat. 17° 47’ N., and long. 67° 3’ W. Amphihelia oculata Epw. & H. "Numerous specimens, showing much variation, The most common form agrees exactly with Prof. Duncan’s Figs. 1, 2, and 3 of Pl. XLV. of the “ Porcupine ” Madreporaria, and is similarly deformed by a parasitic annelid ; this has apparently the tendency to smooth out the striz. Another variety, free of parasites, grows into long branches, with alternate calicles, forming regular zigzags. Often each calicle gives out two opposite ones, one of them forming the main branch, the other beginning a side branch on the same pattern. Prof. Duncan’s Fig. 1, Pl. XLVI., shows this mode of growth, but not with the regularity of some of our specimens. It has also been represented by Seguenza and by Moseley.. Old branches of this form become much thick- ened and compressed. Both forms are the same, since they are found in the same specimen. The strie vary much, and I doubt if they present a sufficient character to separate A. oculata and ramea. Amphihelia sculpta, Seg., to which I referred specimens dredged last year, is the same. Range from 164 to 892 fathoms, in seven stations, off Guadeloupe, Dominica, Martinique, Grenadines, and Grenada. Axohelia mirabilis Ducn. & Micu. Very common, and rather variable. None were found agreeing with Axohelia Schramm ; but those I had identified as A. myriaster and A. dumetosa I have now good reason to believe are only differences of age. Old specimens are generally coarsely striated, somewhat like the figure of A. myriaster given by M.-Edwards and Haime ; while younger branches are mostly granulated. As Axohelia myriaster is an East Indian species, I shall use provisionally the name first used by Duchassaing and Michelotti for the West Indian species ; but having seen no specimen of the former, I cannot tell in what they differ. Among the varieties there is one with slender branches and calicles, raised on conical projections, as in Oculina varicosa. Specimens obtained from the telegraph cable off Santiago de Cuba, in 90 fathoms, by Captain Cole of the Telegraph steamer “ Investigator,” are stunted, sharply striated, the strize almost ribbon-shaped. The calicles are sunken, often deformed, and some- times surrounded by shallow open cells, twice as numerous as the septa, producing a resemblance to some of the double-walled palozoic corals. Many specimens are deformed by barnacles occupying the end of the branches, which soon become entirely covered by the coral, with the exception of a small opening. 108 BULLETIN OF THE . Range from 56 to 262 fathoms, in twenty-seven stations, off Santa Cruz, Saba Bank, Montserrat, Guadeloupe, Dominica, Martinique, St. Vincent, Grena- dines, Grenada, and Barbados. Madracis asperula Epw. & H. Range from 60 to 248 fathoms, in six stations, off Santa Cruz, St. Kitts, St. Vincent, and Grenada. Solenosmilia variabilis Dunc. None of our specimens show the blue coloration noticed by Prof. Duncan in northern specimens. Range from 120 to 452 fathoms, in six stations, in Old Bahama Channel, off Montserrat, Guadeloupe, St. Lucia, Grenadines, and Barbados. Lophosmiilia rotundifolia Epw. & H. . There is a fine series of specimens of all ages, which positively contradict Duchassaing’s opinion that the original specimen of M.-Edwards and Haime was the young of a compound coral, which he has unnecessarily re-named Oxysmilia rotundifolia. Occasionally two or three individuals grow in a group, but are not to be called compound for that reason. The lamellar three- lobed columella is rarely seen as regular as in M.-Edwards and Haime’s | figure ; it usually thickens in the old, and often becomes irregular. The foot thickens very much by additions of exothecal cellular roots arranged in con- centric circles, as in Thecocyathus. The dissepiments are few, but rather thick. Lophosmilia urena Duch. is probably the same. Range from 42 to 163 fathoms, in eight stations, off Santa Cruz, Montserrat, Dominica, Grenadines, and Barbadoes. DASMOSMILIA Povrt. nov. gen. Corallum turbinate, with very thin wall, false palli and columella formed by lobes of the septa ; rudimentary endotheca. This genus is proposed to receive the two species heretofore named by me Parasmilia Lymani and Parasmilia variegata, which evidently differ very much from the typical Parasmilia. The figure of one of the septa of P. Lyman in my “ Deep-Sea Corals,” Pl. VI. Fig. 10, represents well the principal generic character. MUSEUM OF COMPARATIVE ZOOLOGY. 109 Dasmosmilia variegata Pourt. Parasmilia variegata Pourt. Bathycyathus elegans STUDER. Plate II. Figs. 11 and 12. The wall measures only 0.003 in thickness in a full-grown specimen; few specimens are therefore obtained entire, and fewer yet are free from deformity from former breakages. Most fragments seem capable of forming new indi- viduals by completing lost parts ; sometimes two individuals rise from the septa of one fragment ; in that case one of them is most probably a true bud. In 164 fathoms, off Grenada. Parasmilia fecunda Linpsrr. (Pourt. sp.) Celosmilia fecunda Pourt. Cenosmilia arbuscula Pourt. Blastosmilia Powrtalesi Dunc. Anomocora fecunda STUDER. From the examination of a large number of specimens it appears conclusively that Celosmilia fecunda and Cenosmilia arbuscula are but accidental variations of the same species. The arbuscula form is the normal one, represented by shorter and more massive corallites, with well-developed columella; the fecunda form has grown under circumstances which forced it to elongate beyond measure, and at the same time to form all its parts, such as the wall, the septa, and the columella, thinner and more scanty. The extreme forms are easily distinguished as very different, but there are numberless inter- mediate ones, often parts of the same stock. With regard to the apparent budding, numerous alcoholic specimens show that Lindstrom’s remark, that the young do not arise through gemmation, is perfectly correct. There is not a single case where the young grows from a living specimen ; the supposed parent has in every instance the appearance of having been dead for some time. It is, however, singular, that in many instances the young are grouped with a certain regularity around, and ata little distance from, an older calicle. If, then, the propagation is by eggs, there reinains very little reason for separating this form from Parasmilia proper. Range from 73 to 450 fathoms, in nineteen stations, off Santa Cruz, Mont- serrat, Guadeloupe, Dominica, Martinique, St. Vincent, Grenadines, Grenada, and Barbados. Asterosmilia prolifera Povcrt. Ceratocyathus prolifer Pourt. Paracyathus arcwatus LINDSTR. Plate II. Figs. 9 and 10. A careful revision shows that I committed a double error in referring the specimens in question to the genus Ceratocyathus, and in placing the latter 110 BULLETIN OF THE among the Trochosmiliacee. The specimens of Ceratocyathus ornatus used in comparison are true Caryophyllie, while my Ceratocyathus prolifer is a true Asterosmilia, closely related to Asterosmilia anomala Duncan, from the San Domingo miocene. It is one of the very few connecting links between the West Indian tertiary coral fauna and the recent one, while there are so many between the European tertiary and the present West Indian deep-sea fauna. A specimen with calicular gemmation has three young ones of different ages growing out of its calicle, one of them exceeding the parent considerably in diameter. The latter was still living in the very small part of its calicle left free, and had formed new septa against the outer wall of some of the younger ones. The polyp has a well-developed outer sphincter, which contracts suffi- ciently to cover entirely the tentacles, and close about two thirds of the calicle. I may as well remark here that Prof. Duncan’s supposition, that the office of the pali is to support an extra circle of tentacles, is not borne out in this species, nor in any other paliferous coral of which I have had the opportunity of examining the polyp. The pali generally show themselves through the membrane of the buccal disk, which they appear to support. Range from 76 to 94 fathoms, in three stations, off Grenada and Barbados. Balanophyllia palifera Poort. A vertical section shows that the pali are true pali, separated from the septa by a row of perforations. Large specimens have a few septa of the fifth order. Range from 82 to 164 fathoms, off Guadeloupe, Grenada, and Barbadoes. Trochopsammia infundibulum Pouvrt. A specimen brought up living has the polyp uniformly dark brown, with thick tentacles, slightly different in size, according to their order, and nearly in one circle. There appears to be no muscular circle outside of the tentacles. Range from 291 fathoms, off Grenada, to 424 fathoms, off St. Vincent. Stereopsammia? rostrata Pourrt. Amphihelia rostrata Pourt. This rather abundant coral shows in its younger branches decided Eupsam- mian characters, the cceenenchyma being perforated in the furrows even at a‘ distance from the calicles; the secondaries are shorter than the tertiaries, which meet in front of them. In old specimens this character becomes less distinct, and the perforations are obliterated by an epithecal growth, which is deposited chiefly on the back part of the branches to a thickness of as much as two centimeters. The striz are never obliterated by it, but the fine spines disappear gradually, and old calicles and foreign bodies become quite covered by it. The projection from the side of the calicle, on account of which the specific name was given, is very variable, even in the same stock, some calicles MUSEUM OF COMPARATIVE ZOOLOGY. 111 showing but a slight thickening of one of the septa, while in others as many as five septa are swelled out, forming a protuberance equal to the diameter of the calicle. As the columella is absent or nf ction rudimentary, this coral is placed provisorily in the genus Stereopsammia, though it differs setabisiel from the typical species. Dendrophyllia profunda Pourt. ought to be placed in the same genus. ‘Stereopsammia rostrata is one of the largest West-Indian deep-sea corals; some of the stocks when entire must have been an inch thick and a foot high. Range from 164 to 580 fathoms, in three stations, off Santa Cruz, St. Lucia, and Grenada. Dendrophyllia Goesi Linpstr. Like Mr. Lindstrém’s specimens, ours are simple, like Balanophyllia; one of them shows two buds on its sides. As Lindstrém remarks, it is difficult to draw the line between Balanophyllia and Dendrophyllia. In the case of Dendrophyllia cornucopia, for instance, we have in the collection large specimens without any tendency to bud, which if known alone would certainly be classed with Balanophyllia. From 250 to 400 fathoms, off Havana. Dendrophyllia alternata Pourt. n. sp. Plate II. Figs. 3 and 4. Corallum branching more or less in a plane; calicles on the sides, alternate. Coenenchyma striated, finely and sharply granulated, feeling rough to the touch. Calicles prominent, and somewhat expanded at the border. Coste very rough, spines perforated, but not very distinct near the calicle, at a little distance from which they merge into the striz of the stem. Septa thickened and rough on the edge of the calicle, coarsely granulated on the sides, often bent and warped. Four cycles, six unequal systems, the fourth cycle being unequally developed. The primaries are slightly thicker, and more exsert than the others. Fossa rather deep ; columella small, but very compact, and projecting from bottom of fossa, formed of four or five combined parts. The largest branch is 10 cm. high, 12 mm. in diameter at thickest part; it seems to have been part of a still larger branch. Calicles 5 mm. in diameter. This species is allied to D. ramea, but is smaller, and has no terminal calicles different from the lateral ones. Range from 150 to 189 fathoms, in three stations, off Guadeloupe, Martinique, and St. Lucia. Dendrophyllia cornucopia Pourt. Range from 73 to 400 fathoms, in five stations, off Havana, Grenada, and Barbados. VOL. ‘VI. — NO: 4 9 112 BULLETIN OF THE Bathyactis symmetrica Mos. Fungia symmetrica Pourr. The tentacles are rather small, and are arranged, as in the true Fungie, at variable distances from the ae according to the order of the septa, but as in the latter are very symmetrical ; the tentacles are also at regular distances, according to the cycle. Range from 116 to 400 fathoms, in thirteen stations, off Havana, Santa Cruz, Montserrat, Guadeloupe, Martinique, St. Lucia, Grenadines, Grenada, and Barbados. Guynia annulata Dunc. Range from 150 to 357 fathoms, in three stations, off Saba Bank, Montserrat, and Martinique. Dunecania barbadensis Pourt. I group this and the following species together provisionally, but not under the name of Rugosa, a group which requires revision, and among the characters of which a tetrameral arrangement of the septa cannot be maintaincd. It is rather singular that no other specimen of Haplophyllia has been obtained in all the dredgings taken in West-Indian waters. It is much to be regretted, as the typical specimen was somewhat deformed. Range from 103 fathoms, off Barbados, to 191 fathoms, off Martinique. Anthemiphyllia patera Pourt. Plate II. Figs. 5 and 6. The description in my former paper was based ona single specimen. A number of fine ones obtained this year in the same locality renders it Ree, to modify it in several points. The outer surface is covered with a smooth porcellaneous epitheca, without distinct border, concealing the coste nearly up to the border of the calicle, where they become somewhat prominent, and beset with short spines. There is a coarse spongy columella, with flat fasciculate or oftener foliaceous surface. The interseptal chambers are open down to the bottom, but constricted very much at intervals by a series of stout half floors or shelves projecting from the columella outward. The wall is thick. The transversely flattened spines of the septa are similar to those of Diaseris crispa; similar ones are seen also in well-preserved specimens of Montlivaultia bormadensis. I am still in doubt about its affinities ; in general appearance it resembles an Antillia, but the absence of a complete endotheca is against placing it in that proximity. It may possibly be related to Discotrochus. From 250 to 400 fathoms, off Havana. MUSEUM OF COMPARATIVE ZOOLOGY. rls ANTIPATHARIA. In determining the Antipatharia of this collection, an attempt was made to use the differences in the shape of the polyps, and in the dis- position and form of the spines, to draw characters for a much-needed revision of their classification. It is generally conceded that the division into genera, based mainly on the mode of branching, as estab- lished by Milne-Edwards and Haime, is not satisfactory. I have used in former papers the name Antipathes as sole generic designation, and shall continue to do so for the present, until more material is accumulated. In Plate III. will be found figures, drawn with the camera, of the spines of the West Indian species, and of a few others for comparison. It will be seen that there are at least two different types, — the tri- angular compressed, and the more cylindrical. The latter are generally more densely set, even assuming sometimes a brush-like . appearance, as in Antipathes humilis. (Plate III. Figs. 18 and 19.) They are also unequal on the two sides of the pinnules, being longer on the side occupied by the polyps, with a few very much longer ones around the latter. The triangular spines are disposed regularly in a quincuncial order around the pinnules, and in a cleaned specimen nothing indicates the place formerly occupied by the polyps. The only exception to a more or less spiral disposition of the spines with regard to the axis I have found in Antipathes (Cirrhipathes) Desbonni, where the spines are in regular verticils. (Plate III. Fig. 6.) Duchassaing and Michelotti have figured the same arrangement in Arachnopathes paniculata D. & M. (non Esper), which I have not seen. In Plate III. Fig. 24, the spines of a very large apparently undescribed species from Mau- ritius are figured, showing frequently a secondary point, somewhat like shark’s teeth. With regard to the polyps, the drawings herewith presented have the disadvantage of having all been made from alcoholic specimens, in various stages of contraction. Still there are differences from one species to another which cannot be ascribed to that cause. There appears to be a connection between the shape of the polyps and the shape and dis- position of the spines. Those species which have triangular spines have polyps with longer tentacles than those with cylindrical spines, with a greater tendency to become regular in shape, though there are some in which the polyp is very oblong in horizontal outline, as in A. tetrasticha. 114 BULLETIN OF THE Very long tentacles are found in A. spiralis. In very few instances the tentacles are found retracted, as figured by Lacaze Duthiers; in most cases they are simply contracted, and in many species they are probably not retractile at all. The following species were collected : — Antipathes (Cirrhipathes) Desbonni Ducu. & Mica. Plate III. Fig. 6. In former papers I had used this name for a Cirrhipathes bent in a spiral, although the above authors state their species to be straight. In this collection there is a straight form, besides a large number of spiral ones ; and as they are specifically quite distinct, I retain the above name for the species more fully described here. Antipathes growing in clusters, a dozen or more stems from an expanded root, each stem undivided, slender, straight or slightly bent, but not spiral, hollow near the end. Spines small and rather blunt, in regular verticils, of which there are about thirty to a centimeter, each one composed of about twenty spines. On the older parts of the stem the verticils lose somewhat of their regularity, but can always be recognized with a little attention. Ver- tically the spines are also disposed in straight rows, not winding spirally around the stem. The tips of the stems are membranous and collapsed when dry, being thin and hollow, with the spines already quite distinct. Longest stem, 70 cm.; diameter at base, 1.5 mm. Only one dry cluster was obtained in station 155, 88 fathoms, off Montserrat. Antipathes spiralis Pavvas. Plate III. Figs. 5, 25, and 26. This is the species I had formerly referred to A. Desbonnt Duch. & Mich. It may be different from Pallas’s species, but I have now no means of com- parison. Our specimens are all very slender, wound nearly from the base into spirals 10 to 20 cm. in diameter. The spirals are either from right to left, or the reverse, and sometimes change from the one to the other in the same specimen. The spines are short, triangular, compressed, and never in verticils, but in quincunx. The longest specimen is 3.20 m. long, 4 to 5 mm, in diameter at the base. The polyps are alternately large and small, have very long digitiform ten- tacles, much longer than have been figured of any Antipathes before. (Plate IIL. Figs. 25 and 26.) The figure represents them as they are frequently dis- posed, the larger polyps alone being visible, the smaller ones showing only in the profile view. At other times the tentacles are very much shortened and stiffened, and stand out like those of A. arborea figured by Dana. MUSEUM OF COMPARATIVE ZOOLOGY. 115 The ccenosarc on the back part of the branch shows transverse canals more transparent than the rest, in the spaces between successive polyps. This species is very common, having been obtained in twenty-three stations, in depths ranging from 45 to 878 fathoms, off Havana, Santa Cruz, Montserrat, Martinique, St. Vincent, the Grenadines, Granada, and Barbados. Antipathes (Rhipidipathes) tristis Ducu. Plate III. Fig. 10. Of this delicate species there are several good specimens, 3 or 4 inches high ; the branches are very slender; anastomoses among them are not plentiful, they are more properly adherences. The spines are sharp, triangular. (Plate III. Fig. 10.) The polyps are small, have short digitiform tentacles, and moder- ately prominent mouth ; the two lower tentacles are sometimes laid around the mouth, as figured in A. spiralis. Range from 45 to 226 fathoms, in eight stations, off Santa Cruz, Montserrat, Martinique, St. Lucia, and Barbados. Antipathes thyoides Pourr. n. sp. Plate III. Figs. 17 and 31. Densely flabellate, but entirely without adherences of the branchlets, which ramify from the sides of the branches without showing any regular pinnate arrangement. The finer branchlets show an apparent succession of swellings, produced by the larger spines surrounding the polyps. The spines are of the cylindrical type, unequal, with a few very long ones about the proximal end of every polyp. (Pl. III. Fig. 17.) The polyps are of the sessile type, with very short tentacles. (PI. III. Fig. 31.) The largest specimen spreads 20 cm. in height, and 30 cm. in breadth. In 124 fathoms, off St. Vincent. Antipathes picea Poort. n. sp. Plate III. Figs. 9 and 29. Branching, flabellate, the branches With four rows of pinnules, two of which remain generally small and simple, while the two others develop more and give the pinnate appearance to the branches. These larger branchlets are again beset with small pinnules on one side. This is precisely the same arrangement as in A. tanacetwm, from which it differs by the spines, which are in the latter species about three times as long as broad at the base, while in A. picea they are about as high as broad. The polyps are small, with a large spherical buccal knob and flattened tentacles, with slightly incised border ; when strongly contracted they appear globular. They are thickly beset with bundles of lasso-cells. On the thicker branches the polyps are rare, and have 116 BULLETIN OF THE distant and rudimentary: tentacles ; on the main stem very few buccal knobs are found, and these entirely destitute of tentacles. Height of specimens 20 to 25 cm. 86 Nab Station 260, 291 fathoms, off Grenada. Station 286, 7 to 45 fathoms, off Barbados. ) Antipathes tanacetum Pourt. n. sp. Plate III. Fig. 13. The mode of branching and the spines have been described under the pre- ceding species, and the differences pointed out. This species remains mostly with a simple stem, rarely branching a few times, and has much the appearance of a leaf of tansy or yarrow. On the lower part of the stem the spines become very slender and branching like miniature deer-horns, forming a velvety covering, which becomes filled with grains of sand, sponge spicules, &c. The polyps were badly preserved, but evidently very small. Most specimens have a parasitic worm, resembling very much, and perhaps identical with, the one which produces the tube in A. colwmnaris; here however, it remains applied to the stem, partly protected by the branchlets, but producing no change in their growth. Range froni 88 to 170 fathoms, in eight stations, off Santa Cruz, Montserrat, Dominica, Martinique, the Grenadines, and Grenada. Antipathes filix Pourrt. Plate Ill. Figs. 15 and 16. My original description of this species was based on simple and younger stocks; it, however, branches in a subflabellate manner, spreading 30 to 40. cm., more in breadth than height, and assuming then a general appearance with A. myriophylla of the East Indies, with which I have confounded it when in this state (Bull. Mus. Comp. Zool., Vol. V. No. 9). It differs from it-greatly in the arrangement of the pinnules and spines. The long spines surrounding the polyps are beset with little knobs at the end, giving them a rugose appear- ance. In A. myriophylla (Pl. III. Fig. 23) the spines are all equal. The polyps are small and inconspicuous, and of the type of those of A. humilis (Pl. III. Fig. 32). The differences between this species and A. abietina are not great, the spines and polyps presenting no particular differences. The latter species may be distinguished, if it is not considered a mere variety, by its greater stiffness, and by being regularly pinnate instead of having pinnules in every direction. Range from 76 to 287 fathoms, in twenty stations, off Montserrat, Martinique, Dominica, Guadeloupe, St. Vincent, the Grenadines, and Barbados. MUSEUM OF COMPARATIVE ZOOLOGY. pay Antipathes eupteridea Lamx. Plate III. Fig. 11. The very scanty description of this species, the type of which came from Martinique, leaves it a little doubtful if our specimen can be referred to it. Lamouroux compared his specimen to a peacock’s feather. Ours is branching, resembling very much some of the larger Plumularide, — Cladocarpa paradisea Allm., for instance. The specimen, the main stem of which was dead at the top, must have been about 40 to 50 cm. high. The pinnules are 40 mm. long. The spines are nearly cylindrical, rather dense, subequal, very little longer about the polyps. The polyps are very small and sessile. ~ Station 203, 96 fathoms, off Martinique. Antipathes salix Pourt. n. sp. Plate III. Fig. 8. Irregularly branching, with long slender pinnules, not disposed in any par- ticular order, the whole appearing somewhat like a miniature weeping-willow. The spines are equal, long triangular, somewhat hooked upward, rather close set. On the larger branches they form longitudinal rows, more or less regular. The polyps are very small and inconspicuous, of the sessile type. It resembles somewhat Aruchnopathes paniculata Duch. & Mich. (non Esper.), but is more flexuous, has no coalescent branches, and the spines are not in verticils. : Station 171, 183 fathoms, off Guadeloupe. Antipathes rigida Pourt. n. sp. Plate III. Fig. 12. A small specimen, differing from the preceding only in being stiffer, with thicker pinnules and occasional coalescences of branches. The spines are very much like those of the preceding species, only not quite as densely set. The polyps are of the same type. Station 273, 103 fathoms, off Barbados. Antipathes columnaris Ducu. Plate III. Fig. 3. The spines are very small, triangular, and blunt, somewhat longer at the tip of the pinnules. The polyps are rather abundant on the network forming the tube for the parasitic worm. , Range from 73 to 861 fathoms, in sixteen stations, off Guadeloupe, Marti- nique, Dominica, Virgin Gorda, St. Lucia, St. Vincent, the Grenadines, and Barbados, 118 BULLETIN OF THE Antipathes humilis Pourt. Plate III. Figs. 18, 19, and 32. The most densely spinous species which has come under my observation. Range from 76 to 262 fathoms, in four stations, off Montserrat, Grenada, St. Vincent, and Barbados. | There are several species described by Duchassaing and Michelotti, and by the former alone in his Revue des Zoophytes et Spongiarres des Antilles, Paris, 1870, which are too briefly characterized for identifica- tion. The large species which I had formerly referred to A. dissecta D. & M. is A. glaberrima Esper. Fig. calcar. Fig. Fig. Fig. Fig. os 16. MUSEUM OF COMPARATIVE ZOOLOGY. 119 EXPLANATION OF THE PLATES. PLATE I. Deltocyathus italicus, showing passage from variety Agassizii to variety Deltocyathus italicus, variety a, Agassizii, section magnified. Coste of the same, magnified. Deltocyathus italicus, variety 8, section magnified. “< ‘s “¢ y, calcar, section magnified. “ rT ‘* 6, section magnified. my rT: ‘¢ 6, costz magnified. ‘ “ *« 6, calicle magnified. Paracyathus laxus, profile, nat. size. Te “s ealicle, ee 6 ‘¢ section, Be Caryophyllia communis, variety costata, nat. size. “ “$ ~ ‘‘ ealicle, nat. size. Desmophyllum Riisez, nat. size. Stenocyathus vermiformis, portion decalcified, magnified. ‘a re or two segments separated, to show interrupted connections at the centre. bj kd OQ Ga" de" da’ da’ da" da’ da" da" da’ da" da" da" da’ gi ~ rae ee ee) SS ae fal ped at SS) rer BEV CONROE PLATE II. Stephanotrochus diadema, specimen with the polyp aa in alcohol. Stephanocyathus variabilis, * * Dendrophyllia alternata, nat. size. i es calicle magnified. Anthemiphyllia patera, section 3 66 66 septa 66 Paracyathus flos, profile, nat. size. = ‘* calicle, big Asterosmilia prolifera, calicle, nat. size. 6é 6é profile, sé Dasmosmilia variegata, profile, nat. size. = a calicle, a Flabellum Moseleyi, profile, nat. size, se - calicle, . 120 Pig: “1s Fig. 2. Fig. °S. Fig. 4. Fig. 5. Fig. 6. Big: i, Fig. <3; Fig. 9. Fig. 10. Fig: ‘11. Fig. 12. Fig. 13. Fig. 14. Fig. 15. Fig. 16. Fig. 17. Fig. 18. Fig. 49, Fig. 20. Fig. 21 Fig. 22. Fig. 23. Fig. 24. Fig..'25. Fig. 26. 1 * BULLETIN OF THE MUSEUM OF COMPARATIVE. ZOOLOGY. ig. Zi . 28. ig. 29. . 80. ods . 32. PLATE III. Pinnule of Antipathes tetrasticha, magnified 10 diameters. Je “ glaberrima, be ey ss columnaris, cig a 6é 6é lenta, 6é 6é Stem of Sf spiralis, “ | Sot 9 “ Desbonni, oe of Membranous tip of Antipathes Desbonni, <* oa Pinnule of Antipathes salix, e 5 be ee picea, 6é ce ‘“c 66 tristis, GG ‘6 “ i eupteridea, si ms 6c 66 rigida, 66 7 os oF tanacetum, ka ei “ ee abietina, € PE rT rT filix, 66 cc Spine of af Jilix, magnified 230 diameters. Pinnule of ‘“ thyoides, magnified 10 diameters. oH = hunvilis, a o upper view, ‘6 66 ‘ 66 66 “6 lower view. a oe Fernandezit, zis pe 6é 66 arborea, 6é 66 sf e reticulata, . id oe myriophylla, ie zi Pinnules of Antipathes, sp. from Mauritius, magnified 10 diameters. Side view of contracted polyps of Antipathes spiralis, showing smaller polyps concealed under the arms of the larger, magnified 10 diameters. Upper view of contracted polyps of Antipathes spiralis, the small polyps showing but one or two tentacles ; the tentacles of the large one in the middle are now contracted. Polyps of Antipathes lenta, magnified 10 diameters. €é oe 6eé ce 66 66 6é ce 6é ce glaberrima, ‘* % pi Col, 66 73 > tetrasticha, ‘* “ thyoides, ot mH humilis, a ig CAMBRIDGE, February 6, 1880. A.Meisel, Lith : f i Lay : J 1 >» é 7 fem a a lo we " ” f E : : ‘ one i ; = 1 . : } on fy ha \ y ey AS if ral ra eae ‘ i i ek Tom i Or ay f dj ale ah hea \y 7 \ ar | ae Fi y Nee ha i rs ‘ : , i a , 1 ; q ' \e “ 1 9 hike { ai os 2M wo rime : ? P ' bs ee f { \ £ ii, i ’ i ; } & # , Sa : By iy { M ‘. } \ 1 . P ne * ‘ ‘ j > i! P «q * £0) 4 { J / i oa wy ia, | Aan | l iw Raa A. Meisel, Lith i ‘ , i \ ‘ , " ' Feil f i . ‘ tne, = i } % = v i ! i " 4 2 j ’ t { / « © i 4 = { x j aa Ll P ~ ~~» Pe A a aA Ss aA OR So o0U a 6 ne per’ od re ww ~~ 7 wi wey wee ITS D peice ‘ lx! — soSe Se Se OS = a a > Ps a ~ _ =< 2 2 2. SS Na been 8 : = = => 1 a ed oe PV PATE Pir yvyyy ee A ee a ap & N Reo a a ey ey 02 py Dapp ey = = = << en Ae iat Oy ey alr he ay SP” OL dado day 1 ——_ 4 F 2 a Ss — La VOM TV YWIS TH 7 FF N roel A A DS 4 ee a DAXD AAA cl bass | 2 ‘inten Se eS as bee” Pe oat eae) - = 5 2 Ta a gem aaa cel ey en nt nt a a A Meisel, ith A i igs’ re j J " ’ : ; No. 5.—The Ethmoid Bone in the Bats. By Harrison ALLEN, M. D. A coMPARISON of the ethmoid bones of the bats, upon which I have been of late engaged, has resulted in defining some interesting points in the anatomy of the organ of smelling in these animals. Awaiting opportunity for framing more elaborate descriptions, I propose formulat- ing an account of the peculiar appearances of the ethmoid in the various families. I may here state, that, in every example I have examined, the detail in the arrangement of the scrolls of the ethmoid bone has yielded characters by which the genera and even the species can be readily determined. The genera examined are the following: Pteropus, Hpomophorus, Rhinolophus, Phyllorhina, Megaderma, Nycteris, Antrozous, Plecotus, Corimorhinus, Vesperugo, Vesperus, Scotophilus, Atalapha, Vespertilio, Natalus, Miniopterus, Emballonura, Taphozous, Noctilio, Molossus, Nyctinomus, Chilonycteris, Mormoops, Macrotus, Vampyrus, Schizostoma, Phyllostoma, Carollia, Glossophaga, Artibeus, Vampyrops, Stenoderma, Chiroderma, Sturnira, Brachyphylla, Centurio, and Desmodus. The identifications of Dobson (Catalogue of the Chiroptera Br. Mus., 1878) have been accepted in framing the above list. In all the genera examined, the ethmoid bone is composed of a ver- tical lamella projected from the cribriform plate, to which in most in- stances there is appended an outer (lateral) horizontal scroll. (1.) In its simplest form, the vertical plate bears upon its median surface one or more rudimental scrolls. Examples of this variety are seen in the Nycteride. In Nycteris, Rhinolophus, Phyllorhina, and Megaderma spasma, the rudimental scrolls are horizontal ; but in Mega- derma frons they are vertical. The outer (lateral) scroll, which is present in NVycteris and Phyllorhina, tends to be directed inward. (2.) In the next degree of complexity met with, the vertical lamella resembles the foregoing, but possesses a small lateral scroll, which arises independently from the cribriform plate. The vertical plate retains upon its median aspect two vertical rudimental scrolls. Example, the genus Hmballonura. VOL. VI. — NO. 6 122 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. (3.) In the third degree of complexity the vertical plate is revolute anteriorly, and (as seen from above) is sub-triangular or cylindroid in form. It retains upon its median surface two supplemental horizontal or oblique scrolls. The outer (lateral) scroll is present. The vertical plate may project well in advance of all the other parts, or may be but slightly longer than they. No union exists between the outer (lateral) scroll and the vertical plate of the frontal bone in the orbit. Examples, Vespertilionide, the genus Molossus, its congeners, and Noctilio. Natalus is remarkable for lacking the outer (lateral) scroll. In Molossus, Nyctinomus, and Noctilio the vertical plate projects scarcely at all in advance of the median supplemental scrolls, and never appears on the median surface below the level of the scrolls. In Ves- pertilionide it forms a conspicuous tapering process. It is seen below the plane of the supplemental scrolls in Atalapha noveboracensis and Vesperus noctivagans. (4.) The vertical plate is short and ends abruptly anteriorly. It is visible beneath the supplemental scrolls on the median surface. The outer (lateral) scroll is as long as the vertical, and is united to the ver- tical orbital plate of the frontal bone. Example, the. genus Zaphozous. (5.) The vertical plate is produced in advance of the position of the supplemental scrolls, as in the last-named group, but is compressed from side to side as seen from above, and is not revolute. It bears upon its median aspect posteriorly a lobule. The supplementary scrolls in general appearance are much as in the Vespertilionide. The lateral scroll is cylindroid. Examples, the Phyllostomide. In Desmodus, the lobule upon the anterior portion of the vertical plate is relatively large. (6.) The vertical plate is projected far in advance of the supplemen- tal scrolls, which are horizontal in position and four in number. The lateral scroll is more or less adherent to the vertical plate, or by its outer border to the frontal bone. Examples, the Pteropide. The Pteropide, Nycteride, and some Phyllostomide have a horizontal septum passing transversely from the under free edge of the vertical plate (as it lies beneath the lowest median supplemental scroll) to the nasal septum. The olfactory surface in such forms is thus withdrawn from the respiratory currents, since no direct outlet exists at the pos- terior nares. The above descriptions have been drawn, for the most part, from specimens in the fine collection of the Museum of Comparative Zodlogy, Cambridge, Mass. FEBRUARY, 1880. No. 6.— On certain Species of Chelonioide. By SAMUEL GARMAN. In this notice three species of Sea Turtles are mentioned, of which two are supposed to be new. About three years ago, Richard M. Kemp, of Florida, directed my attention to a peculiar Turtle, commonly called the ‘ Bastard,” found in'the Gulf of Mexico, and said to be across between the Green and Loggerhead, Chelonia mydas and Thalassochelys caowana. At a later date he secured for the Museum a pair of fine specimens, which furnish the material for a description given below. In consideration of the great interest Mr. Kemp takes in matters pertaining to natural history, it is most appropriate that the species he has been the means of bring- ing into notice should bear his name. There is considerable likelihood that the other species, of which de- scriptions are given, have heretofore been considered as one, Chelonia virgata. If this has been the case, a very slight comparison of the characters assigned will convince any one of the necessity of separation. Of the various names that have been applied by different authors to C. virgata, none can be said with certainty to belong to the flat, broad species which has probably been associated with it. Consequently, it is thought better to apply a name not previously employed in connection with either of them, thus avoiding confusion, rather than to make use of a synonyme concerning which there will always exist more or less doubt. Thalassochelys Kempii sp. nov. Body depressed, short, broad, subcircular, with a slight concavity over the lateral marginal plates of the carapace, and without the prominent rounded hump on the vertebral series over the pelvis or shoulder girdle, as in T. caou- ana. Head intermediate in size between that of T. caouana and that of Chelonia mydas, crown slightly convex. There is a shallow depression from the eye forward. Looking from above, the outline of the face is much more convex than in either of the species cited. A low, broad, rounded ridge extends from the nostrils to the point on the end of the beak. The lateral outline of the jaws VOL. VI. — NO. 6. 124 BULLETIN OF THE is very convex forward. Upper jaw without serrations, lower outline forming a sigmoid curve, convex posteriorly, and concave near the extremity, where it suddenly descends to the sharp point at the symphysis. The greatest con- vexity occurs at a point below and in front of the eye. Lower jaw strong, without serrations, upper edge concave, curving upward in a point on the symphysis. Frontals, two pairs. Vertical small, narrow, hexangular. Two supraorbitals on each side. Interparietal large, broad, surrounded by thirteen plates (9-13). Postorbitals, three, upper small, lower narrow, elongate. Cara- pace with little or no indication of a hump on the first or ultimate vertebral plates, outline slightly straightened over the hind legs, indented over neck and arms, with five shields in each series of costals and the vertebral. Anterior vertebral shield short and narrow, second to fourth narrow and long, posterior longer and wider. First pair of costals small. Marginal plates, twenty-seven, anterior very narrow, becoming wide on the flanks from the fourth. From the middle of the body back the marginal shields are subequal, excepting the caudal pair, which are wider, but without being produced beyond the general outline. Eight or ten of the posterior marginal bones of the skeleton are joined by suture to the broad costals, making for the hinder half of the cara- pace nearly solid bone. Paddles medium, each with two nails, anterior long and narrow, posterior short and broad, margins indented between the digits. In one specimen the width and length are equal, twenty-six inches; in the other, the width is twenty-nine inches, while the length is only twenty-eight. Both are quite aged, as is shown by the ossification of skull and carapace, and by the worn appearance of jaws and scales. Distinguished from 7’. caouana by the short, round body, low humps, mar- ginal plates, narrowness of head across occiput, and swollen jaws; from T. olivacea by shape of head, swollen jaw, and plates of the carapace. The compression of the anterior portion of the head of T. olivacea at once separates the species. “The Bastard Turtle are common. We know that they come on the beach to lay in the months of December, January, and February, but cannot tell how often, or how many eggs they lay at a time. They can be secured quite readily, but are not sought for. Hawksbill, Loggerhead, and Green Turtle lay in April, May, and June.” (Kemp.) Some of the characters by which this turtle is distinguished from caouana and olivacea are of more than specific importance,— namely, shape of head and body, and skeletal peculiarities. According them a subgeneric value, the habitat suggests the name Colpochelys, from xéAmos, a gulf. This will give to this species the name Colpochelys Kempwt, Kemp’s Gulf Turtle. Chelonia depressa sp. nov. Young. — Body a broad oval; head large, rounded posteriorly, occiput convex, flattened between and compressed in front of the eyes. Jaws not ser- rate (in very young), upper with a shallow notch in front, lower with a sharp MUSEUM OF COMPARATIVE ZOOLOGY. 125 curved prominence at the symphysis. Carapace broad, arch comparatively low, with three low ridges, slightly concave near the margin. Paddles broad, rounded on the margins. Adult. — Body broad, depressed, subelliptical, broadest near or behind the middle, concave near the iateral margins, flattened over the second to the fourth vertebral plates ; head larger and broader than that of C. mydas or C. virgata, broad posteriorly, convex on the occiput, flattened between and compressed in front of the eyes. Upper jaw not serrated, outline nearly straight, with the notch at the symphysis almost obliterated, vertically grooved on the inner face. Lower jaw serrated, bearing a curved fang-like prominence on the symphysis. Carapace broad and spreading posteriorly, arch very low. Paddles comparatively small, anterior narrow and pointed, posterior short, truncate, indented between the digits. One pair of elongate frontals. Ver- tical small, short, broad, pentagonal, acute-angled in front. Supraocular large, broad. Interparietal broader than long, surrounded by seven plates, vertical, supraoculars, parietals, and occipitals. Postorbitals four (8-4), lower large. Plates of carapace not imbricate, smooth in young and adult, costal series four each, five vertebrals, and twenty-five marginals. Sternal plates thirteen, in two series of six each, preceded by a small triangular plate at the neck. Lateral plates of plastron four on each side, preceded by a pair of small, and these again by several smaller brachials. The specimens described are from the East Indies and North Australia. Applying the line to the shell the Aus- tralian specimen measures in length 364 inches, and in width 30 inches ; its height is 9 inches. A specimen of C. mydas has a length of 393 inches, a width of 343 inches, and a height of 11 inches. / C. depressa differs much from the species described by Dumeril and Bibron as C. virgata. It is less truncated and more deeply indented in front than either of the other species of the genus. A transverse section across the middle of the body is not what would be called roof-shaped, but more of the shape of a bow of considerable curvature, a portion of the middle of which is straight, and of which the extremities are sharply turned upward. The sides are not strongly arched, and the cross-section of a large specimen could not be described as forming an open angle. The broadness of the head, the marked difference in shape from that of C. mydas, and the concavity near the lateral margins, could not have escaped the notice of the authors of the Erpétologie Générale, if there were specimens of this species at hand. Their description applies either to the species renamed by Dumeril and Bocourt C. Agassiz, or to one much more closely allied to it than that described above. If the separation of C. Agassiziz from C. virgata of authors is right, there exists a third species of Chelonta in the Northwestern Pacific and the northern part of the Indian Ocean. The specimens from which the de- scription in the Erp. Gen. was taken were said to be from Teneriffe, Rio Janeiro, Cape of Good Hope, New York, and the Indian Ocean, which dis- tribution can leave little doubt that they were of more than one species. 126 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. Chelonia Agassizii Dumerit & Bocourt, 1870. ? Chelonia virgata ScHWEIGGER, 1814. Chelonia virgata AGAssiz, 1857. Carapace subcordiform, considerably arched, narrow posteriorly ; margin with a shallow indentation over neck and each arm, and a deeper one over each leg. Head moderate, about the size and shape of that of C. mydas, more compressed and pointed in front of the eyes than that of C. depressa. Upper jaw not serrate on the edge, with grooves on the inner face corresponding to the teeth on the lower, with a slight notch in front. Lower jaw serrated on the edge, bearing a prominent curved point on the symphysis. Serration of jaw not apparent in very young specimens. Frontal plates one pair, sometimes subdivided. Vertical small, narrow. One supraocular on each side. Inter- parietal moderate, surrounded by seven plates; supraoculars and vertical in front, and a pair of large plates behind on the occiput. Postoculars four. Cen- tral plates of carapace thirteen, vertebral series five, anterior and posterior wider, posterior costals and vertebrals sometimes divided; marginals twenty- five, posterior sometimes fused. The anterior and posterior plates of back are rather suddenly bent downward near the margin. The tail of the male is longer ; it appears that the pointed extremity of the carapace is also more elongate in this sex. Specimens described from the eastern portion of the tropical Pacific. CAMBRIDGE, March, 1880. No. 7.— Contributions to a Knowledge of the Tubular Jelly-fishes. By J. WALTER FEWKES. I. The Development of the Tentacular Knob of Physophora hydrostatica. THE anatomy of those animals known to the zodlogist as the Sipho- nophore, or tubular Jelly-fishes, has been carefully studied, and minutely described. I present certain points in which my observations or conclu- sions differ from those of other naturalists. I have also discussed at length the limits and synonymy of the genus Halistemma, since I think it embraces animals with generic differences, and I conclude with a brief mention of North American Siphonophore and Velellidz, adding three genera to those already described for our coasts. The development of the structures which have received the name of tentacular knobs has a certain interest, particularly the different stages in growth of that per- haps most complicated of all, the knob of Physophora. The development of these structures long since attracted attention, and Claus * twenty years ago (1860) published a description, with figures, of the younger stages of the knob in Physophora hydrostatica. Keferstein and Ehlers, to whom science owes so many discoveries in regard to these Jelly-fishes, followed this work with certain corrections and additions of the most important character. Their investigations were made upon a species of Physophora called P. Philippi, identical with or only distinguished from P. hydrostatica by the possession of lateral appendages to the external walls of the knob. The account which they give in most particulars applies also to P. hydrostatica, which’ has furnished me the material for my studies of the developmental history of the tentacular knob in this genus. The growth of the knob of Physophora, although quite simple, is more complicated than that of any other Siphonophore. I have only, how- ever, considered it necessary to figure a few stages assumed in this growth, illustrating the peculiar asymmetrical form of the involucrum, and the embryonic appendages to the sacculus, which are provisional in * Ueber Physophora hydrostatica nebst Bemerkungen itiber andere Siphonophoren. VOL. VI.—wNO. 7. 1 128 BULLETIN OF THE their nature, and give the early condition of the knob a likeness to that of certain other genera of Physophoridee. The knob of Physophora hydrostatica originates, like that of other tu- bular Jelly-fishes, as a simple bud, hardly distinguishable from the earlier condition of all structures in the Siphonophores. In its place of origin it resembles the genus Agalma, for it forms on the ciliated base of the feed- ing polyp, and is in fact a proliferation of the walls cf that part. Whether all Physophore knobs originate from the same relative position is an open question. In Rhizophysa filiformis we have several of the polypites nearest the float with naked tentacles, from which the knobs bud, never arising from the base of the polypites. Of course these undeveloped appendages in the singular Rhizophysa may be looked upon as tasters,* a supposition hardly probable ; or it is also possible that they correspond with somewhat similar structures between the nectocalyces of Apolemia uvaria. In the well-known genus last mentioned the polyp-like parts between the swimming-bells appear to have no filaments like those found on the tasters of other Siphonophores. The taster-like bodies near the float of Rhizophysa are undeveloped feeding polyps. In the very earliest stages the Physophora knob is composed of layers which are apparently two in number. The differentiation of other layers takes place later in the course of the development. At first we find only ectoderm and entoderm in the walls of the knob. This simple bud elongates into a flask-shaped body, at the base of which the cavity becomes enlarged, imparting to this region a more or less spherical shape. (Pl. I. fig. 2.) From the ectodermic wall of the enlargement thus formed arises the involucrum. An éxamination of this region, even at an early period (Pl. I. fig. 3), shows that a differentiation has begun, and that the ectoderm has divided into two layers, one of which appears as a collar * The word taster, to designate peculiar structures among the Siphonophores, is perfectly applicable in the case of Physophora. In other genera the designation ‘“‘Saftbehalter” may seem better; but here in Physophora their function seems dif- ferent from that of the same part in most of these animals. The filamentary append- age to the taster in Physophora, although very easy to see, has been overlooked by several naturalists. (See Kolliker, Schwimmpolypen von Messina. Vogt, Siphono- phores de Nice. Leuckart, Siphonophoren von Nizza, p. 106.) According to Kefer- stein and Ehlers (/. ¢c., p. 31), these appendages to the taster were discovered by Philippi, but were omitted in the descriptions by naturalists who followed him until the investigations of Sars. In his Anatomy of Physophora, Claus (1860) speaks of them (p. 17), but has no representation of the filament in his figure of the genus. (Claus, Ueber Physophora hydrostatica nebst Bemerkungen iiber andere Siphonophoren, Zeitsch. f. Wiss. Zool., Bd. X. p. 1, fig. 1. Philippi, in Miiller’s Arch. f. Anat. u. Physiol., p. 61, Taf. 5, fig. 4. Sars, in Middelhavet’s Littoral Fauna, p. 4.) MUSEUM OF COMPARATIVE ZOOLOGY. 129 around the base of the knob. If we watch the growth of this collar, which is the outer differentiated layer of the ectoderm, it will be found to gradually grow down around the sacculus until it has almost com- pletely enclosed it, leaving, however, an opening at the distal pole of the knob, through which the end of the sacculus, or certain appendages to the extremity of this organ, project. (PI. I. figs. 4, 5.) Meanwhile, the sacculus has passed through certain changes, the most important of which is a coiling up of itself within the envelope of the involucrum, and the formation at its extremity, where it projects through the opening of the involucrum, of certain appendages of a provisional nature. The earliest condition of the sacculus is simply the terminal transparent part of the flask-shaped body already mentioned. It is now a complicated organ armed with lasso cells, and with its walls highly colored. The provisional structures at the distal end of the sacculus (Pl. I. figs. 4, 5, 6, 8) are mentioned and figured by most of those who have studied the young knob of Physophora. They have been seen in both species, but do not appear to exist in the fully de- veloped form of the knob, either in P. hydrostatica or P. Philippi. The accompanying growth of another part of the young knob is destined to change materially the appearance of the whole, as well as the relative development of the parts. This change takes place contemporaneously with the enclosure of the sacculus by the involucrum, and the appear- ance of those provisional terminal filaments which I have already men- tioned. The alterations of form to which I refer are as follows. The proximal or basal part of the spherical-shaped expansion of the young knob enlarges on ong side, and in such a manner that the knob as a whole assumes an asymmetrical shape. (Pl. I. fig. 4.) This want of symmetry is brought about by an unequal growth in the two sides of the basal part of the knob itself. In a still more developed stage of the Same structure the inequality in growth has gone still further, and the enlargement lengthens and extends along the side of the sacculus, now coiled on itself, carrying with it the former place of attachment of the sacculus, which is to be found at the opposite pole from its former junc- tion,” (Pl. I. figs. 5, 6.) Meanwhile the knob is approaching its fully-grown form, and the ter- minal filaments become absorbed ; the opening at the distal pole of the involucrum closes or is very much reduced in size, and the enlargement in the spherical cavity, which earlier gave the asymmetrical form to the whole knob, appears as a simple tube following down along the side of the knob from the pedicel to the place of attachment of the sacculus, at 130 BULLETIN OF THE the opposite end from its original junction. In the structure formed by these changes we have the fully-grown condition of the complicated knob of this Jelly-fish. (Pl. I. fig. 7.) The resemblance of certain of the earlier stages in the growth of this organ, or individual if one so designates it, to the adult in a different genus is very great. Athorybva has a tentacular knob with many points of resemblance to the undeveloped forms which have just been described. The figures of the knob of this genus, as given by Gegenbaur, Kélliker, and Huxley, show a close likeness to the younger stages of the knob in Physophora. While emphasizing this asymmetrical growth of the knob of the young Physophora, and suggesting a likeness to the same structure in the genus Athorybia, I recall the figures of the knob in the younger stages of an Agalma, called by Leuckart Agalma clavatum. As Claus suggests, this species is probably the young of Agalma Sarsit. Leuck- art’s figures of A. clavatum show a knob which assumes a similar asym- metrical shape to that which exists in the knob of Athorybia. . This naturalist* has already made the comparison of a tentacular knob of A. clavatum with the same structure in Athorybia. The comparison seems to me a good one, and does not prevent a comparison of both to the undeveloped tentacular knob of Physophora hydrostatica. A like- ness is further indicated by the existence in each genus of terminal fila- ments on the sacculus, provisional to be sure in Physophora, but none the less definitely pointing out the relation of the structures under con- sideration.t II. The Mantle-Tubes of Apolemia uvaria and Gleba hippopus. A wish to find out the homology of the somatocyst of the Calyco- phores led me to a study of the chymiferous tubes of the swimming-bells throughout the tubular Jelly-fishes. Especially in Apolemza and Gleba, from their aberrant forms, I hoped to find some facts bearing on the solu- tion of this question ; and when I came tosee the former of these genera for the first time, my thoughts were turned to the question of its mantle- tubes. This genus, in many respects allied to the Calycophoride, is a true Physophorid; yet, in the published description of its nectocalyces, I find no mention of any structure which, I think, can be truly known as the * Siphonophoren von Nizza, Pl. XIII. Fig. 5, p. 91. + I find these structures in hydrostatica more leaf-like than they are represented in Keferstein and Ehlers’s plate of Physophora Philippi. MUSEUM OF COMPARATIVE ZOOLOGY. 131 mantle vessel. The four radial tubes of the bell, and the appendages to the lateral pair, have been well figured and described. Leuckart seems to liken rudimentary offshoots of the lateral vessels to mantle-tubes. I do not think these offshoots more than very distantly comparable with that special pair of vessels, which arises from a tube medially placed in the bell, connecting the junction of the radial system with the stem cavity of the animal. Such mantle-tubes, for instance, as are to be found in Agalma, Gleba, or other genera, do not seem to have been observed in the nectocalyx of Apolemza. I think, however, that I have found in the bell of Apolemia a structure homologous to the man- tle-tubes in the Physophoride, and represented in the Calycophore by the somatocyst. The mantle-tubes in Apolemza are difficult to make out, but seem to differ only in their size from those in Gleba. Radial tubes in these two genera, however, differ very greatly; for while in the one they reach a development hardly equalled among Siphonophores, in Gleba, where the cavity of the bell is very shallow, and the nectocalyx itself is more of a bract than a swimming-bell, the chymiferous tubes have a mini- mum development. So rigid is the nectocalyx of Gleba that the walls admit of little motion, and most of the propulsion is done similarly to that of Circe and other Trachynemide, by a movement of the velum, a crescentic-formed vail surrounding the opening into the shallow bell cavity. As a consequence, the radial system is quite diminutive in size. Nowhere among Siphonophores better than in the genus Gleba do we find a nectocalyx (PI. III. Figs. 4, 5), when fully grown, so closely resem- bling a bract, and it seems to me that a better proof of the homology of the central tube of the bract or covering scale with the mantle vessel of a nectocalyx could hardly be desired. Apolemia has a float and a true Physophorous nectocalyx,* while Gleba has no float, and is radically different from the Calycophoride, although its multiplicity of nectocalyces is a true characteristic of the Physopho- ride. Therefore I think that the Hippopodidee should make one of the three great groups into which the Siphonophore may be divided, and be considered an equal division with the Physophoridz and Calyco- phoridee. * T figure (Pl. I. Fig. 1) a fragment of an Apolemia, without nectocalyx or float. I have already published a representation of the nectocalyx of Apolemia. Proc. Bost. Soc. Nat. Hist., Vol. XX. 132 BULLETIN OF THE III. The Tubes in the larger Nectocalyx of Abyla pentagona. The best description which I have found of the course of the chymif- erous tubes of Abyla pentagona is by Gegenbaur.* At the regular meet- ing of the Boston Society of Natural History, on November 5, 1879, I pointed out the existence in Abyla of a supplementary tube, which takes an origin from the junction of one of the radial vessels with the circum- velar tube, and extends diagonally across one quadrant of the bell, ending in an enlargement of a peculiar kind. I also indicated the difficulties which present themselves to a determination of an homology between the chymiferous tubes in Abyla and other nectocalyx-bearing Siphono- phores, on account of these supplementary tubes. The bilateral sym- metry shown quite well in the swimming-bells of other Calycophoride, as Epibulia, Diphyes, and Praya, in the Hippopodide, and in Agalma, Agal- mopsis, Halistemma, Apolemia, and Physophora of the Physophoride, does not appear in the different spherorneres of Abyla. In all cases except Adbyla, bilateral symmetry, as referred to a plane passing through two opposite chymiferous tubes of the bell, and the ventral line of the stem, is very easy to make out.. The want of symmetry in Adbyla is the result of a covering in of the “ Lingskanal” by a growth from one of the bounding ridges of the bell. A like covering of the canal is to’ be seen in Monophyes, where the nectocalyx is hemispherical, with none of those marked elevations and projecting points continued beyond the opening of the bell which are so prominent in Abyla, and to which it owes both of the specific names pentagona and trigona. I have noticed no varia- tion from a normal arrangement of the chymiferous tubes in Monophyes. (Pl. III. fig. 6.) IV. On Halistemma, Agalma, and Agalmopsis. The adoption of the generic name Halzstemma has now become almost universal, and seems necessary for a proper understanding of the genera of Siphonophores, about which there has existed considerable confu- sion. The following animals have, I think, been erroneously placed in this genus; viz. Halistemma tergestinum, Claus, and Halistemma carum, Haeckel. Huxley, in ‘Oceanic Hydrozoa,” proposed the name for cer- tain forms of tubular Jelly-fishes, with elongated axes, biserial rows of swimming-bells, and naked tentacular knobs with a single terminal fila- ment. The genus Agalma, by his classification, was to include those the * Neue Beitrige zur Naheren Kenntniss der Siphonophoren. Nova Acta Carol., Vol. XXVII., 1860, pp. 349 - 356. MUSEUM OF COMPARATIVE ZOOLOGY. lao tentacular knobs of which had two lateral terminal filaments, while Stephanomia had but a single filament of this kind, although the last two genera have a biserial row of nectocalyces and an involucrum. There are certain other characteristics of this genus which are not so well marked as those already given by Huxley. I refer to the character of the tentacles, and more especially to the position of the sexual organs. Tentacles such as we find in Agalma do not seem to exist in the genus Halistemma, but the tentacular knobs have very long pedicels, longer than in other Physophoride, which allow the knob to project so far be- yond the covering scale as to resemble tentacles very closely. Accord- ing to some observers true tentacles do exist in the genus Halistemma. For instance, Leuckart says that Kolliker missed the true tentacle, and mistook the pedicel of the knob for a tentacle itselfi* Kolliker’s figure of Agalmopsis punctata, which is the same thing as Halistemma rubrum, shows the absence of the tentacles very plainly. My observations on the tentacle agree with Kolliker’s, yet his figure of the animal is not com- plete, in that he failed to represent the sexual system. The female sexual organs I shall later describe. (PI. I. figs. 3-5.) Leuckart* fig- ures a true tentacle in Halistemma. What Claus describes as Hali- stemma tergestinumt does not seem to belong to Halistemma in the sig- nification given to the generic name by its founder, Huxley. It belongs rather to Huxley’s genus Stephanomia in all its structure, but especially in the character of its tentacular knobs, a feature of greatest importance in the classification of the Physophoride. Haeckel (Entwickelungsgeschichte der Siphonophoren) proposes a di- vision of the Agalmidz which has some advantages, although to use the trifid character alone of the tentacular knob as a basis of his sub- family Crystallodacea separates those with an involucrum, and places Agalmopsis (Stephanomia, Huxley) with Forskalia and Halistemma. These last have no involucrum in the tentacular knob, and the former has sexual organs arising at the base of a polyp, while the latter has these same structures midway between two tasters. There does not * Leuckart, Zur Nahern Kenntniss der Siphonophoren von Nizza, Taf. XII. fig. 15. When I studied Halistemma, I did not know of this difference of observation by Kolliker and Leuckart. + 1. Metschnikoff, Proc. So. Fr. Nat. Moscow, Vol. VIII.; Studien der Medusen und Siphonophoren, Zeitsch. f. Wiss. Zool., Bd. XXIV. 2. Claus, C., Ueber Halistemma Tergestinum, &c., Wien, 1878. Mittheilungen uber Siphonophoren und Medusen Fauna Triests, Zool. bot. Gesell. Wien, Tom. XXVI. 3. Eschscholtz characterized the genus Agalma, ‘‘ Tentacula ramulis clavatis : clava apice bicuspidata.” 134 , BULLETIN OF THE seem to be sufficient ground for such a subdivision. I think it would be better if all were placed with Athorybia, as separate genera, in the Agalmidz, and no subdivision of the group of any other kind at present attempted. / In the Neue Beitrdge, Gegenbaur substitutes the name Stephanomia for that of Yorskalia to designate a well-known form. He says, however, nothing about the genera Halistemma and Agolmopsis, and neither appears in his scheme of classification at the end of that work. Possibly he considers both. as simply species of Agalma. That which Claus in the last year (1879) has described and figured under the name of Agalmopsis utricularia, ought to be a new genus rather than a species of Agalma or Agalmopsvs.* There seems no reason why the name Stephanomia, which Lesson ap- plied to both Stephanomza contorta and Apolemia uvarva of later authors, should designate the form with a biserial row of nectocalyces that it now does. Apolemia (PI. I. fig. 1) is a well-marked genus. Leuckart adopts the name Forskalia of Kolliker in his Siphonophoren von Nizza, and int his Zoologische Untersuchungen applies the name Stephanomia to the same genus. He rightly says of the so-called Porskalia that it was first described by Milne-Edwards under the name of Stephanomia contorta (Siphonophoren von Nizza, p. 93). St. delle Chiaje’s use of the generic name, in a description of Stephano- mia ophiura, although hardly accurate enough to be quoted in this dis- cussion, should be mentioned. His designation of a species as ophiwra is still retained in the nomenclature, and the form is easily to be known from contorta, from which even the fishermen of Messina distinguish it, although they affix to both a characteristic name, “ Pinie di Mare.” Kolliker (Siphonophoren von Messina, p. 18) says that Lesson is wholly in error, ‘Wenn er die Stephanomia contorta und prolifera von Milne-Edwards zu derselben (Apolemia uvaria) zieht.” In the Nachtrag to the same work he says: ‘“‘Immer hin bleibe ich bei dem Genus For- skalia das nach einem vollstandigen Thiere gebildet ist und kann der Name Stephanomia fiir das nur unvollstiindig bekannte Thier bleiben fiir das er von Peron zuerst aufgestellt wurde.” The ‘ unvollstandig bekannte Thier” was that same form whose anatomy Huxley later pub- lished under the name which Peron gave it, although he says that Peron’s sketch has “no scientific value.” What animal Peron had will * Claus, Agalmopsis utricularia eine neue Siphonophore des Mittelmeeres, Arbei- ten aus dem Zoologischen Instituts der U. Wien und der Zoologischen Station in Triest, Bd. II. 2 Heft. x MUSEUM OF COMPARATIVE ZOOLOGY. 135 always remain problematical, and there is no good reason to identify the form studied by Huxley with it. In the Grundziige der Zoologie, 3 Auf., p. 237, Claus includes in the family of Agalmidz Forskalia (Stephanomia, M. E.), Halistemma, and Agalmopsis. He, like Haeckel, mentions Vanomia cara as a species of Halistemma, and says that Stephanomia (Peron) is included in the same genus. Packard follows Claus in this reference of Vanomza to Hali- stemma. . In Nanomia cara, the first formed structure in the larva, according to Mr. Alex. Agassiz, is the float, as in Agalmopsis (Stephanonua, Metsch.). In Halistemma, according to Metschnikoff, the swimming-bell and float develop together from the very first. Although it is possible that the float is simply a modified Medusa bell or nectocalyx, no one would mis- take the young of Halistemma for that of a Vanomza larva. As Metschni- koff has already pointed out, Vanomia in its younger stages resembles the genus Agalmopsis* (Stephanomia, Metsch.). Huxley’s classification of the Siphonophore, with a verbal change, is the best which has been proposed as far as the Agalmide are concerned. We can retain the three generic names Agalma, Agalmopsis, and Halistemma. That would keep Eschscholtz’s genus to designate & Physophorid with a trifid tentacu- lar knob, the Agalmopsis of Sars with a single terminal filament on the same structure, and Halistemma, a form the tentacular knobs of which do not have involucra, and the tentacle is replaced by the pedicels of the tentacular knobs. In addition to the genera Agalma, Agalmopsis, and’ Halistemma, I would include Athorybia among the Agalmide, on account of its embryonic likeness to Agalma. It may possibly be simply the young of this genus. The only other Physophorid, except Stephanomia (Yorskalia), where we have a multiserial necto-stem, is Physophora tetra- * Notwithstanding Sars figures three radically different kinds of knobs in his genus Agalmopsis, a condition only observed, with this exception, in Rhizophysa and the larval forms of certain Agalmide, his figures 5, 6, on Plate V. are among the earliest, if not the first, representations of a tentacular knob with an involucrum and a single terminal filament. I retain, therefore, the name which he has given for the Jelly-fish with this characteristic, particularly on account of the exact use of Stepha- nomia by Milne-Edwards (Ann. d. Sci. Nat. 1841, Tom. XVI. p. 217). See also Leuckart’s note, Siphonophoren von Nizza, p. 93 ; and Huxley, Oceanic Hydrozoa ; Sars, Fauna Littoralis Norvegie, 1846. In Middelhavet’s Littoral Fauna, where all descriptions of Siphonophores are simply numbered, and with no subdivision, Agalma rubrum (A. punctatum, Koll.) is followed directly by Agalma Sarsii, a species with a trifid tentacular knob. In that work Sars makes no mention iof the genus with a covered (by an involucrum) tentacular knob and a single terminal filament. 136 BULLETIN OF THE stica of Philippi (Miiller’s Arch., 1843). Leuckart thought (Stphonophoren von Niza, p. 106, note 2) that this species ought to be made a new genus. I have not found the form redescribed by any naturalist since Philippi, and, although I have frequently taken Physophora hydrostatica and Philippi in my excursions on the Mediterranean, I have never seen tetrastica. Gegenbaur’s view, to which Keferstein and Ehlers also in- cline (Zoologische Beitrage, p. 30, note 7) seems a good explanation of the apparently multiserial arrangement of nectocalyces spoken of by Philippi. Gegenbaur suggests that this multiserial character of the necto-stem in tetrastica is brought about by an accidental twisting of the necto-stem, a thing which often happens in Physophora, Agalma, and Halistemma. An Agalma which answers to Leuckart’s description of A. clavatum was found in such numbers as to give me almost a perfect series between it and Agalma Sarsw. It was not possible, however, for me to raise the lat- ter from the former, but the evidence which have mentioned seems enough to prove the identity of the two. Claus * has already made a similar suggestion. I have frequently taken at Villefranche a Jelly-fish identical, I think, with that which has been described by Claus as Hali- stemma tergestinum, and by Metschnikoff as Stephanomia pictum. A description of this animal, which I had formerly thought new to science, I had prepared without any intimation of the previous work of these naturalists. S. pictum was taken by Metschnikoff from the same locality where my studies were made. I think from the character of the ten- tacular knobs that we have in this interesting Siphonophore a true Agal- mopsis as I have limited the genus, or a Physophorid with an elongated stem, no part of which is enlarged into a sac as in Physophora, and which is furnished with only a biserial row of nectocalyces. In addi- tion it has a tentacular knob possessing an involucrum and a single filament. Metschnikoff’s change of the Jelly-fish described by him, which is probably the same, from the genus /alstemma, to which he at first referred it, to the genus commonly known as Stephanomia, was well made. The feature which distinguishes Agalmopsis (Stephanomia, Metsch.) picta from Halistemma, together with those already mentioned, is the position of the sexual organs (Pl. I. figs. 1, 3, 6), and, less definitely, the small size of the covering scales as compared with the nectocalyces. The crimson and orange sexual organs in /. tergestinum, as Claus figures them, and as I have also observed, are clustered, both male and female, at the base of a taster (Pl. I. fig. 6), the male mounted on an * Zeitsch. f. Wiss. Zool., Bd. XII. p. 559. MUSEUM OF COMPARATIVE ZOOLOGY. 187 especial stalk, and not separated from the taster, as in H. rubrum. The bracts are small, and so transparent that at first sight one is inclined to doubt their existence in Agalmopsis picta, while in Halistemma they are large and conspicuous. This feature effects very considerably the rela- tive forms of the two Jelly-fishes. All along the necto-stem and polyp-stem of Agalmopsis picta, more especially, however, upon the former, there are to be found in the ecto- derm, as Claus has already mentioned, bright crimson pigment spots more clearly marked than is generally the case with similar spots on the stem of other Siphonophores. Two of these pigment spots, together with a finger-like process near them, also exist on the young nectocalyces. In very young swimming-bells there are three of these pigment spots. They occupy a position similar to that of the pigment spots of other hydroid Medusee, at the junction of the lateral and superior * tubes with the circumvelar vessel. There are very interesting highly refractile red spots of a problematical function covering the bracts in Agalma Sarsit and Agalma clavatum. (Pl. I. fig. 2.) These bracts, from the place of attachment and the twisting of the stem, form a well-marked spiral around the polyp stem of the animal. The spots on each side of a cen- tral line are arranged on every scale in irregular rows, extending longi- tudinally across the bract, each pigment spot being enclosed in a cell. These peculiar pigment spots of the covering scales, represented remotely also in some genera, as in Apolemia (Pl. I. fig. 1), by elevations com- posed of clusters of cells on the surface of the bract, are the most ap- parent structures in the transparent bract of 4. Sarszz, since with that exception there is hardly any coloration in the covering scale. In A. clavatum, the sexually mature young of A. Sarszz, only four rows of these pigment spots occur, as Leuckart has shown. When the bracts which bear these paralleled rows of spots are detached from the axis, their color changes to a yellow, and a fluid of the same color exudes into the surrounding water. I have not been able to find any mention of this rupture of the cell wall and discharge of a yellow fluid when the bract is detached, in the descriptions by other naturalists. I think these scale cells belong to the ectodermic layer. * A nomenclature of the different spheromeres of the nectocalyx of a Siphonophore would simplify a description of the bell. As paired chymiferous tubes opposite each other have resemblances in their course from their relation to a plane passing through the dorsal and ventral line of the stem, they may be called lateral tubes, and the respective sections of the bell in which they lie, lateral spheromeres. The remaining spheromeres, according to their position in relation to a float, where such exists, may be called the superior, or the inferior, corresponding with a proximal and a distal. 138 BULLETIN OF THE The pigment spots mentioned in the nectocalyx of Agalmopsis picta have no resemblance to these peculiar bodies on the bracts, nor do they change their color when the swimming-bell is detached. The presence of such spots on the younger bell of Agalmopsis picta, and so little devel- oped on the adult, rank them among patterns of embryonic coloration, examples of which are not unknown on other structures of these animals. Stephanomia * (Forskalia) has a similar large yellow spot, which persists in the adult nectocalyx, at the junction of radial and circular tubes. The different stages in development of the female sexual organs of Halistemma have never been described or figured. Kolliker,t in his plate illustrating this genus, does not even represent these parts, and Leuckart} figures the female organs as a botryoidal structure, at the apex of a single polyp-like stalk. In several specimens, in addition to a struc- ture of this kind, we have, as I have figured (Plate II. Fig. 3), others with the stalk on which the botryoidal mass is borne bifid at its extrem- ity. This is probably simply another stage in development of these organs. As Leuckart well says, the sexual organs in Halistemma have no direct connection with the tasters; still, the female structures, at times, arise very near them.§ * The single yellow pigment spot at the junction of radial and circular tubes in Stephanomia (forskalia) has on each side a finger-like process, and also, separated from these only by a short distance, an additional pair of the same rudimentary ten- tacles, as they may be called. The pigment spot is mentioned by Kolliker, who also calls attention to one pair of these tentacles or processes. He says: ‘‘ Der Pigment- fleck ist insofern interessant als bei keinerandern Siphonophore Pigmentirungen de Schwimmglocken beobactet wurden.” (Schwimmpolypen von Messina, p. 4.) + Kolliker, Schwimmpolypen von Messina, Tab. IV. + Leuckart, Zoologische Untersuchungen, Tab. II. fig. 14 ; Siphonophoren von Nizza, Tab. XII. fig. 15. § Claus says (H. Tergestinum, &c., p. 45) : ‘Wo man bei verwandten Agalmiden die Sprossung der Geschlechts-traubchen am Stamme beschreiben findet representirt entweder der Stiel des Tréaubchens einen Taster dessen Endabschnitt kurz und ver- kiimmert bleibt oder aber der Tasterschlauch hat sich von Stiele gelost und ist abgefal- len.” The resemblance to a taster of the stalk upon which the botryoidal female organs of Halistemma are borne, is very small. However, in Agalmopsis and Stephanomia (Forskalia) we find the sexual system at the base of the true taster, which seems to support Claus’s suggestion. Huxley, who had not seen the genus Halistemma when ‘Oceanic Hydrozoa ” was written, says of reproductive organs that they are like those of Stephanomia, and are attached directly to the ccenosarc. The sexual organs have no similarity in point of attachment, as can be seen from my figures of these two genera (PI. II. figs. 1, 3) ; for while in the case of Halistemma they arise directly from the stem, in Agalmopsis (Stephanomia) they are united to the base of the taster. x MUSEUM OF COMPARATIVE ZOOLOGY. 139 V. Notice of a few Siphonophore and Velellide from the East- ern Coast of the United States. Up to the present time few forms of either of these groups of Jelly- fishes have been described from the waters of our bays and sounds. They seem to be only occasional visitors, blown into the neighborhood of-our shores from mid-ocean, or brought there from the tropics by the Gulf Stream. The wealth of tubular Medusz which one finds in the Mediterranean is unknown on New England coasts or in Charleston Harbor, localities in which these animals have been best studied. Upon many single excursions on the quiet bays near Nice, in Southern France, I have taken eight different genera of Siphonophore ; but their rarity is so great at Newport that seldom have more than one or two genera been taken by me in the same day ; and a whole summer, in which I was almost daily upon the water, has passed without the observation of a single genus. A similar case of absence of all pelagic animals happened at Villefranche, last November. In that month, although I was on the water daily, I observed not only no Siphonophores, but also none of those Heteropods and Pteropods which later appeared in such numbers. Certain of the Siphonophore, however, are more abundant with us than in Ville- franche, Naples, or Messina. Physalia caravella is now rarely taken in numbers by naturalists at either of these stations; but many examples of Physalia arethusa may be found almost any summer in Vineyard Sound or the entrances to Narragansett Bay. The well-known Physalia arethusa is the most common of New Eng- land Siphonophores. It was long ago described by one of the pioneers in the study of Jelly-fishes, and later beautifully figured by Prof. Agas- siz in the Contributions to the Natural History of the United States. Prof. McCrady* describes a form, Physalia aurigera, which is consid- ered by Mr. Alex. Agassizf as the same species. In the Catalogue of the North American Acalephe, the list of places from which speci- mens of Physalia arethusa had been taken includes localities all the way from Cape Cod to Florida, and beyond in the West Indies. The two floating Hydroids, Veledla and Porpita, so closely allied to the Tubularians and known as the Velellide, are also found in our waters. The problematical genus Rataria,t by some supposed to be the young of Velella, in swarms of which it is generally found, and by others an immature Porpita, I think has not been described from our coast. I * Gymnopthalmata of Charleston Harbor, 1857. + North American Acalephex, 1865. + Pagenstecher, Zeitsch. f. Wiss. Zool., Bd. XII., 1863. 140 BULLETIN OF THE find no mention of it from New England waters. According to Agas- siz, our Velella is Velella mutica of Bosc. Of that identification there seems no doubt, considering where the animal which Bose described was found ; but, as Pagenstecher* and Delle Chiaje suggest, it is difficult to see exactly what Bosc meant by his other species, tentaculata. The for- mer of these authors says Bosc called the Veledla of Linné and Lamarck mutica, while the species spurans of Forskal received the name tentacu- lata. Mr. Alex. Agassiz mentions a V. septentrionalis from our Pacific coast. Some of the material for the earliest descriptions of the Siphono- phorze and Velellidze was collected in the Pacific Ocean, and near our western shores, and we should naturally expect these species taken by early voyagers from those localities. Porpita I have never seen alive in our waters, but have a dried speci- men preserved on paper after the manner of a plant, taken by a sailor not far from Nantucket. Prof. McCrady describes a species of Por- pita from Charleston Harbor, not very different from Guilding’s Porpita (Polybrachionia Linneana), which he calls Porpita Linneana. He is inclined to think it a new species. The only known member of the long-stemmed Siphonophore, provided at one end with a float or air-bladder, which has been described from New England waters, is Agalmopsis cara (Nanomia cara, A. Ag. ; Ste- phanomia cara, Metsch.; Halistemma carum, Haeckel, Claus, Packard, and others). This animal was first described by Mr. Alex. Agassiz, to whom we owe so much of our knowledge of the Jelly-fishes of our waters. The drawings and descriptions of the development which he gives are not only the earliest of this particular genus, but, with those of Claus, Leuckart, Kélliker, and Gegenbaur, of the embryology of the Siphonophoree as a whole. As I have already said, Haeckel considers Nanomia cara a species of Halistemma, and places it under this genus in his table of the Agalmide. He seems to have been followed by Claus, who adopts the name /7/. carum in his Grundziige der Zoologie. When Mr. Agassiz described the form he said it was closely related to Agalmopsis as well as Halistemma, but that the mode of arrangement of the swimming-bells and the nature of the tentacles of the feeding polyps show undoubtedly that it cannot be placed in the same genus as Agalmopsis, having in mind Sars’s genus. Wanomia cara, according to Metschnikoff, as already shown, should be regarded as a species in the genus Stephanomia. The reason for his conclusion, he says, is on account of the resemblance between the larve as figured * Pagenstecher, Zeitsch. f. Wiss. Zool., Bd. XII., 1863. MUSEUM OF COMPARATIVE ZOOLOGY. 141 by Mr. Alex. Agassiz and Kowalevsky. He says: “Die Aelteste von Kowalevsky gezogene Larve mit Luft apparat Magen und Fang faden gleicht so sehr dem jungsten von Alex. Agassiz gefangenen Jugendzu- stande der Nanomia, dass es mir sehr wahrscheinlich ist, dass auch diese Physophoride in die Gattung Stephanomia eingezogen werden muss zumal zwischen beiden eine grosse anatomische Analogie besteht.” The absence of the cap-shaped provisional bell in the very young Manomia shows that it does not belong to the genus Agalma, and the fact that a float and not a nectocalyx is first developed, separates it from Halistemma. Metschnikoff’s conclusion seems to me the most natural one. I there- fore would refer it to the genus Agalmopsis, of which I regard Stepha- noma, as ordinarily used, a synonym. There are certain points in which, following the description by Mr. Alex. Agassiz (North American Acalephe, pp. 200 - 213), Vanomia differs from the other related Siphonophorz which I have studied. He says that the float in this genus contained a globule of oil. I have never seen the genus fully grown in our waters, and can only judge from my studies of most of the other genera of the justness of Metschnikoff’s criticism (Studien der Medusen und Siphonophoren, p. 36) of Alex. Agassiz on this point. If the float does contain oil, I think it an excep- tional case among Siphonophores. The second kind of feeding polyps, as described in Nanomua, are, I believe, simply immature forms of the first, and the tightly-coiled cork- screw parts are only undeveloped tentacular knobs. I have often found the young knobs of Agalma Sarsw and A. elegans clustered in the same manner at the base of a feeding polyp before a true tentacle had been formed. ; The resemblance of the tentacular knob of Nanomia, with its ‘ cnido- fils,” as shown in Mr. Agassiz’s drawing (Fig. 339), to the provisional structures bearing the same name in Agalmopsis picta and the “ Athory- bia stage” of Agalma, is very great. This likeness is a very interesting fact, indicating either an embryonic condition of the adult of Nanomia, or that it is the larval form, sexually mature, of another Siphonophore. The origin and earlier development of Vanomza cara, according to Mr. Agassiz, as a bud from the stem, is, I think, exceptional. In those other Siphonophores whose development is more or less completely known through the studies of Claus, Haeckel, Kowalevsky, and Metschnikoff, we find only an egg development of the new colony. Dana describes (Mem. Amer. Acad., Vol. II. Part I.) a Physophorid from the Pacific Ocean. He calls it Crystallomia polygonata. The 147 BULLETIN OF THE figures which he gives of the tentacular knob seem to show that it is the genus Agalma of Eschscholtz. Haeckel refers it to his genus Crystal- lodes. The whole embryological history of Agalma and Crystallodes, with the exception of the appearance of a yolk-sac in the latter, according to Haeckel, as Metschnikoff says, is very much the same. Dana published his description in 1857, two or three years after the great works by the German naturalists on the Siphonophores of the Mediterranean. I know of two genera of Leuckart’s Calycophoride, a group of Siphono- phores, which appears to me well defined, which have been described from our eastern coasts. In his ‘ Gymnopthalmata of Charleston Har- bor,” Prof. McCrady describes and figures a new diphyozoid, which he names Ludoxia alata, and a new Diphyes, D. pusilla. His Hudoxia alata seems to be the same as /. Lessonw of Huxley. This animal, ac- cording to this prominent English naturalist, is the diphyozoid of D. appendiculata, » synonym of Leuckart’s D. acuminata. The mention which Prof. McCrady makes of Diphyes pusilla is too short to be of ser- vice in distinguishing it from Mediterranean Diphyide. A figure of a Diphyes acuminata from Villefranche may have some interest, especially as its diphyozoid, Hudoaia Lessoni, has been found by me at Newport. Leuckart mentions in his Siphonophoren von Niza an EHpibulia (Galeo- laria), given him by Philippi, and taken from the coast of Greenland. To the Siphonophorous fauna of eastern coasts of North America® I can add a new member of the Agalmide, probably the same as Sars’s Agalmopsis elegans, and the two diphyozoids, Hudoaia Lessona and Diplo- physa inermis. There is a great diversity of opinion among naturalists what Diplophysa is. All seem to be united in the opinion that it is a diphyozoid, but there is an unanswered question of what Calycophore it is the fragment. I mention a few of the opinions. Gegenbaur,t who first described the form, seems to think its resemblance not very dis- tinct from Lrsea truncata of Will. On page 366 of his Neue Beitrdge he says that “Sie (Diplophyse) entsprechen in der Sculptur der Diplo- physen-gattung Praya.” Praya is probably the same as Ersea. Huxley _ (Oceanic Hydrozoa, p. 66) says that Diplophysa inermis has some resem- blance to the diphyozoid Cucubalus described by Quoy and Gaimard, but says he was unable to arrive at any definite opinion as to what animals were included by the French voyagers in their genera Clymba and Cucu- balus. * My observations on American Siphonophores were made in the laboratory of Mr. Agassiz, at Newport, R. I. + Beitrige zur niiheren Kenntniss der Schwimmpolypen (Siphonophoren). MUSEUM OF COMPARATIVE ZOOLOGY. 143 The title of one of Claus’s valuable papers on the Siphonophore is Die Gattung Monophyes und thr Abkimmling Diplophysa, in which he sup- ports the idea that Diplophysa is a diphyozoid of Monophyes gracilis, Cls. He makes Huxley’s genus Spheronectes a synonym of Monophyes. He repeats in his Grundziige der Zoologre, 3 Auf., 1876, that Diplophysa tnermis is a diphyozoid of Monophyes gracilis, as stated above. Metschnikoff (Studien tiber die Medusen und Siphonophoren, p. 46) says, concerning the relationship of these animals, that fragments of the form Praya mermis were described by Gegenbaur as Diplophysa inermis. He bases his idea of the relationship of these two genera on the identity of the larva of Praya, which he describes, with the remarkable genus of Gegenbaur, and more especially on the resemblance in the form of their nectocalyces. He adds also, that both genera are of small size, which cannot, if taken alone, be a very strong argument for their relationship. ¢ VOL. VI.—NO. 7. 2 144 BULLETIN OF THE TABULAR LIST OF VELELLIDA AND SIPHONOPHORA, FROM THE EASTERN COAST OF THE UNITED STATES. VELELLIDA, Velella mutica, Bosc. Acassiz, L., Cont. Nat. Hist. U. 8., Vol. IV. p. 366, 1862. Agassiz, A., North American Acalephe, p. 216, 1865. Velella spvrans. V. tentaculata (2), Bosc. Porprta Linneana, LEss. McCrapy, Gymnopthalmata of Charleston Harbor, 1857. Agassiz, A., North American Acalephe, 1865. Porpita gigantea. FEWKES, Nantucket. SIPHONOPHORA. I. Physophoride. 1. AGALMIDA. Agalma elegans, FEwKrs, Newport. Agalmopsis elegans, SARS, Fauna Littoralis Norvegie, 1846. Agalmopsis (sp. 1). Nanomia cara, Acassiz, A., North American Acalephe, 1865. Halistemma carum, HAECKEL, Ent. d. Siphonophoren. » Stephanomia cara, METSCHNIKOFF, Zeitsch. f. Wiss. Zool., Bd. XXIV., 1874. 2. PHYSALIDA. Physalia arethusa, TIL. Agassiz, L., Cont. Nat. Hist. U. S., 1862. Agassiz, A., North American Acalephe, 1865. Physalia aurigera, McCravy. Mr. Agassiz suggests that this is the same as Physalia arethusa of Tilesius, II. Calycophoride. 1. DIPpHyID&. Diphyes acuminata, Luck. The diphyozoid of this Siphonophore is Zudoxa campanulata, MUSEUM OF COMPARATIVE ZOOLOGY. 145 Eudoxia campanulata, FEwKES, Newport. Eudoxia Lesson, HuxtEy, Oceanic Hydrozoa. Eudoxia alata, McCrapy, Gymn. of Charleston Harbor. Diphyes pusilla, McCrapy, Gymn. of Charleston Harbor. 2. PRAYIDA. Praya inermis has, according to METSCHNIKOFF, the diphyozoid Diplophysa inermis (GEG.). Diplophysa inermis, FEwKES, Newport. In this incomplete list of tubular Jelly-fishes, we miss many of those beautiful forms which are so familiar to the naturalist on the Mediterranean. Extended observations in our Southern bays will probably bring to light the well-known Siphonophores common to all oceans, Apolemia, Abyla, Physophora, and Gleba. Some of these have already been taken in the Gulf of Mexico and Caribbean Sea. Rhizophysa, found in the same localities, may also be ex- pected, brought by ocean currents to our coasts. CAMBRIDGE, April 1, 1880. 146 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. EXPLANATION OF THE PLATES. a, float; b, nectocalyx; c, necto-stem; d, polyp-stem ; e, feeding polyp; jf, taster; g, ovaries; h, testes; 7, tentacle; 7, tentacular knob; a, involucrum; 8, sacculus; 7, pedicel; 5, terminal filaments; X, tentacle of the taster; 7, somatocyst; n, radial tubes; 0, circular vessel; p, covering scale; qg, longitudinal canal; ec, ectoderm; en, entoderm; 7, joint in polyp-stem; s, nectocalyx of diphyozoid ; ¢, crescentic- formed velum in Gleba. The mantle-tubes, somatocyst, and central tube of the bract or covering scale are designated by the letter 7. They seem to be the same structures. PLATE I. Fig. 1, Apolemia uvaria, a part of the polyp-stem, magnified four diameters. The longest stem observed by me was eight feet in length. Figs. 2, 3, 4, 5, 6, 7, different stages of development of the tentacular knob of Physophora hydrostatica. Fig. 3 shows the origin of the involucrum. Fig. 4, 5, 6, represents the provisional form of the knob, and the embryonic terminal filaments. Fig. 7, a knob in the most developed condition. PLATE Ii. Fig. 1, view of Agalmopsis picta from one side, magnified two diameters. The ten- tacles are drawn to the vicinity of the polyp-stem by which the tentacular knobs appear on the upper side of that appendage (an unusual condition.) Fig. 2, covering scale of Agalma Sarsit. Fig. 3, portion of the polyp-stem of Halistemma rubrum, magnified four diameters. Fig. 4, tentacular knob of Halistemma rubrum. The lower extremity of this figure joins figure 3 at the point y. Fig. 6, taster of Agal- mopsis picta. This figure shows the position of the male and female organs in refer- ence to the taster. PLATE III. Fig. 1, Praya diphyes. Fig. 2, Praya, sp. (?) This unknown species of Praya differs from Praya cymbiformis in the equality in size of the nectocalyccs, their tri- angular outline when seen in profile, and the direct course from junction to circular vessel of the radial tubes. The difference between it and Praya diphyes is plainly brought out by the accompanying Fig. 1. It has the somatocyst in but one necto- calyx, and the diphyozoids are crowded together along the polyp-stem, somewhat similar to the conditions among the Agalmide. I incline to regard Fig. 2 as the young of Praya cymbiformis. Fig. 3, Diphyes acuminata. Fig. 4, lateral view of the nectocalyx of Gleba hippopus. Fig. 5, inferior view of a similar nectocalyx. Fig. 6, Spheronectes (Monophyes) inermis. All these drawings are from Jelly-fishes taken in the Mediterranean. e 5. »> SNE, m Boston Tue Heuiotype Printino Co. 126 PEARL 8 Piate IL. re Sse E Aad ANS: E | AN es fe he Ny) IWF Tue Hevioryps PRintina Co. 126 PEart Sn Boston Tae Hevoryee Pruvrina Co. 126 Peart Sr. Boston Plate Jil. No. 8.— (Letrer No.4.) Zo Caruite P. Patrerson, Superin- tendent United States Coast and Geodetic Survey, Washington, D. C., from ALEXANDER AGASSIZ, on the Dredging Operations carried on during part of June and July, 1880, by the United States Coast Survey Steamer “ Blake,” Commander J. R. BARTLETT, . Ss. I gomneD the “Blake,” at Newport, late in June. According to your instructions, we proceeded to the northeastern edge of George’s Shoal, where we ran our first line of dredgings from the 100-fathom line to a depth of nearly 1250 fathoms. Our second line was run to the south- east, off Montauk Point. This was interrupted by bad weather. We were compelled to put into Newport, and completed the line on our return from the South. This line extended to nearly 1400 fathoms. On leaving Newport for the second time we steamed directly. for Charleston, 8. C. A line of dredgings was run from the 100-fathom line normal to the coast directly across the Gulf Stream to a distance of about 120 miles to the eastward of Charleston. Finding that our depth did not increase at that distance, — our greatest depth not being much more than 350 fathoms, — Commander Bartlett thought it prudent to return towards shore, to the so-called axis of the Gulf Stream, and to run a line in a northeastern direction parallel to the coast in the trough of the Gulf Stream. To our great astonishment the depth did not in- crease. We carried from 250 to less than 300 fathoms until we nearly reached the latitude of Cape Hatteras, when in a short distance there was a very rapid drop from 352 fathoms to 1,386 fathoms. A fifth line was run normal to this northern slope of the Gulf Stream plateau, to a depth of 1,632 fathoms. A sixth line was run to the northward of Cape Hatteras, to a depth of 1,047 fathoms. A seventh line was run east off Cape May, from the 100-fathom line to nearly 1200 fathoms. We were greatly disappointed in the richness of the fauna on the lines off Charleston and in the Gulf Stream, owing partly to the very gradual slope of the continent towards deep water, and the strong cur- rent of the Gulf Stream, which sweeps everything off the bottom along its course., There is but little food for the deep-water animals, and it was only along the edges of the Gulf Stream where mud and silt accu- VOL. VI. — NO. 8. 148 BULLETIN OF THE mulated that we made satisfactory hauls on our Southern lines. What was obtained seemed to be a scanty northern extension of tht fauna of the Caribbean Sea and of the Gulf of Mexico between the 100 and 350 fathom lines. It was not until we trawled on the steep slope of the Gulf Stream plateau south of Cape Hatteras, where the bottom was fine mud and Globigerina ooze, that we made a rich harvest again, in striking contrast to the poor hauls along the well-swept rocky or hard bottom of the Gulf Stream to the southward. Along the western edge of the Gulf Stream we came upon several patches of the modern green-sand forma- tion, where the bottom was entirely composed of perfectly clean dead Globigerinee. Although Pteropods were very common at the surface all the way from Charleston to Cape Hatteras, they were only rarely brought up dead from the bottom ; but when the steep slope south of Hatteras was reached they again assumed a prominent part in the composition of the bottom mud. While running the line parallel to the coast from off Charleston to Cape Hatteras, we came twice upon localities where the sounding cup brought up nothing but clean Globigerine, the bottom consisting en- tirely of the modern green-sand to which Bailey and Pourtales had already called attention as forming off shore on the Atlantic coast of the United States. The rapid changes in the character of the mud, as we increase both our distance from shore and the depth, are well shown in the nature of the bottom of the different depths along the short, steep line forming the northern slope of the Gulf Stream plateau traced by the “Blake” from Charleston to south of Cape Hatteras. We very rapidly pass from the comparatively coarse mud to fine and finer ooze, which becomes an impalpable silt in the deeper water beyond 1,000 or 2,000 fathoms, assuming at the same time gradually a lighter color. Among the Tunicates I may mention two new species of Salpz, one of which is interesting, its chain occupying an intermediate position between that of Salpa pinnata and the ordinary Salpa chain of 8. zo- naria or S. Cabotti of our coast. The solitary individuals are gigantic specimens, measuring no less than twelve inches in length. This solitary form is closely allied to S. maxima, but differs from it in the number and arrangement of the muscular bands. The chains grow to a great length, some of them measuring more than ten feet in length and as much as nine inches in breadth. The zodids are arranged as in S. pin- nata, side by side in a single row, extending vertically across the whole width of the chain, and forming a thin ribbon, which when floating is usually slightly coiled like a tape. The zodids of the chain resemble MUSEUM OF COMPARATIVE ZOOLOGY. 149 S. Africana. This species was found at sea from Cape Hatteras as far north as the eastern extremity of George’s Shoal. Among the Acalephs, the most interesting form was a species of Do- decabostricha, Br., the largest specimen measuring no less than nine inches in height. Several specimens of a dark violet (claret-color) were brought up in the trawl, and it is very probable from the systematic aftin- ‘ities of this Medusa that, like its allies, the Rhizostome, it lives on the bottom, rarely coming to the surface. For the genus Dodecabostricha Professor Agassiz established a new family, the Brandtidze, and placed it in the vicinity of the Charibdeide. While it undoubtedly has a general resemblance to the Charibdeide, the structure of the genital pouches and of the lobes of the actinostome shows that it is intermediate between the Aurelie and the Rhizostome proper, combining at the same time structural features only found in the Pelagiz. It is not known where Mertens found the species which is figured in Brandt’s memoir. As we trawled mainly on mud or clay bottoms, but few Hydroids were col- lected. All along the course of the stream we found large quantities of Tri- chodesmium erythreum. On one occasion, north of Hatteras, we passed through an extensive patch of this pelagic Alga, which colored’ the surface of the sea a dirty yellow for a distance of about a quarter of a mile by a hundred yards in width. Among the corals a fine species of Flabellum, probably the Flabellum alabastrum, Mos., and a few species characteristic of the West India seas and of the Gulf of Mexico were found to extend as far north as Cape Hatteras. There were a number of Pennatule and Virgularie collected, probably the same species already described by Professor Verrill from the collections made by the United States Fish Commission, as well as a few Gorgoniz, among which I may mention numerous specimens of Kera- toisis. The Pennatulz and Gorgoniz were all remarkable for their bril- hant bluish phosphorescence, a single Pennatula lighting up a large tub of water. A couple of species of Zoanthus were found in deep water. Among the Actinic large specimens of Bunodes and of Edwardsiz came up from depths of from 600 to 800 fathoms. Among the Echinoderms all the way from Cape Hatteras to the ex- tremity of George’s Shoal, Ophiomusium Lymani were quite common in deep water. Kchinus norvegicus is abundant, and Schizaster fragi- lis extends from deep water inside the 100-fathom line. A species of Asthenosoma and one of Phormosoma were also found in deep water, having the same general distribution as Ophiomusium. A fine species 150 BULLETIN OF THE of Urechinus closely allied to Urechinus naresianus, and several of the rarer species of Starfishes, — Archaster, Porcellanaster, Luidia, Astro- gonium, Porania, Pteraster, and Hippasteria, — were found to extend far into deep water; and beyond 1,000 fathoms, off George’s Bank, we found several fine specimens of Brisinga, as well as three or four species of the remarkable deep-sea Holothurians belonging to the or- der of Elasmopoda; among the Crinoids, Comatula Sarsii? and a few specimens of Rhizocrinus. Although the line to the eastward of Charles- ton, S. C., was commenced off the very home of the Scutellz and other Clypeastroids, it is remarkable that not a single Mellita or Clypeaster was dredged up, either on that line or the line run in the axis of the Gulf Stream as far as Cape Hatteras. LEchinarachnius off George’s Shoal was found to extend to a much greater depth, living specimens having come up in the trawl from a depth of 524 fathoms. | But few Annelids were collected, a few specimens of Nemerteans, and of Calymne; one of the large Eunicide, the tubes of which, sometimes fully fifteen inches in length, often filled the bottom of the trawl when dragging on muddy bottoms, was specially numerous. A number of species of Cephalopods, mainly Northern species already found in shallower waters by the United States Fish Commission, were brought up, many of them from considerable depths. The Gasteropods and Acephala were represented by many of the species collected by the “Lightning” and “Porcupine,” and by the United States Fish Com- mission. Among the Crustacea the most characteristic types were the gigantic Pygnogonidee, a species of Willemoesia, a couple of species of Gnatho- phausiz, Scalpellum, and large Amphipods. Among the Fishes a large collection was made, mainly of Macrouride, including a few new genera, which will be described by Mr. Goode, of the United States Fish Commission. We found cod, extending to a depth of over 300 fathoms (off George’s Shoal). Myxine and Lophius were brought up from 360 fathoms, as well as Sebastes norvegicus. A species of Phycis, from a depth of 233 fathoms, was found to be electric, giving quite a strong shock to Commander Bartlett and myself. It is a small species, about nine inches in length, of a light ashy violet color, with dull yellowish spots along the sides. The absence of siliceous and other sponges in the collections made during this summer is very striking, and although the number of speci- mens of certain species was often very great, yet the continental faune of the northern part of the east coast of the United States is poor when MUSEUM OF COMPARATIVE ZOOLOGY. Lot compared to the wealth of species found in the Caribbean Sea and Gulf of Mexico during the former cruises of the ‘ Blake.” Commander Bartlett did everything in his power to make up for the absence of my assistant, and I was fortunate in again finding on board the older officers of the “ Blake,” Messrs. Sharrer, Jacoby, Peters, and Reynolds, whose industry, energy, and interest in the work has never flagged, and who have now attained a proficiency in deep-sea dredging hardly deemed possible three years ago. Lieut. Mentz and Dr. Persons joined the ‘‘ Blake” during the winter of 1879, and Mr. Duvillard was attached to the “ Blake” as recorder during the first part of our cruise. During this short cruise we made no less than fifty hauls: we accom- plished nearly as much as during the three months of the first cruise in the Gulf of Mexico. As the greater part of the collections made during this cruise of the “Blake” cover the extension into deep water of the ground already in part occupied by the United States Fish Commission, I have arranged with Professor Baird to send the bulk of the collections made north of Cape Hatteras, for final study, to some of the naturalists to whom the collections of the Fish Commission have been intrusted. During the winter of 1879-80, Commander Bartlett, while sounding in the Western Caribbean Sea, made some twenty hauls with the trawl, dredge, and tangles. These collections, made incidentally by the officers of the “ Blake,” show the extension of the continental fauna of the Eastern Caribbean to its extreme western portion. Pentacrinus was found off Santiago de Cuba, and off Kingston, Jamaica. The deep-water fauna was found to be the same as the deep-water fauna of the Eastern Caribbean. | Mr. Bartlett showed that a strong current passing over a ridge, as in the case of the Windward Passage between Cuba and San Domingo, Swept it entirely clean, so that but little animal life was found to live upon it. But immediately beyond this, on the Caribbean side, the mud and silt are deposited in great quantities and animal life becomes plenty again. This, as I have stated above, was also our experience during the present cruise of the “Blake,” while dredging along the so- called axis of the Gulf Stream. . Lieut.-Commander C. D. Sigsbee accompanied us on the “Blake,” to Superintend in person the first trial of his collecting cylinder. It was sent down in 30 fathoms, from 5 to 25 fathoms, with quite a fresh breeze blowing, at about eleven in the morning, in full sunlight, —a time when, with a smooth sea, the pelagic animals would all have been found ” 52 BULLETIN OF THE on the surface. The cylinder was found to work most satisfactorily, and brought up a few Calani, Hydroid Meduse, such as usually occur at the surface. A few slight modifications were suggested by Mr. Sigsbee, and Commander Bartlett recommended the addition of a wire-gauze trap, to facilitate the washing out of the microscopic animals which might be collected. On the Ist of July the Sigsbee cylinder was tried for the second time in Lat. 39° 59’ 16” N., Lon. 70° 18/ 30” W., in 260 fathoms of water. The surface was carefully explored with the tow-net, to see what pelagic animals and others might be found on the surface. There were found Calanus, Sagitta, Annelid larvae, Hydroid Medusz, Squille em- bryos, Salpee, and a few Radiolarians. The cylinder, filled with water which had been carefully sifted through fine muslin, was then attached to the dredging wire, and lowered, so as to collect the animals to be found between 5 and 50 fathoms. The time occupied by the cylinder in passing through that space was 28 seconds. The cylinder was then brought up, . and the sieves and gauze trap carefully washed with water, which had also previously been strained through fine muslin. The water was carefully examined, and we found the very same things which had a short time be- fore been collected at the surface with the tow-net and the scoop-net : nothing different was collected by the cylinder. The Radiolarians (two genera) were perhaps more numerous than at the surface. A slight breeze having sprung up after the surface collections had been examined, the cylinder was then sent down a second time at this same station, so adjust- ed as to collect any animal life to be found from a depth of 50 to 100 fathoms. Not only in this experiment, but in all the subsequent ones, the same precautions were taken in regard to straining the water which filled the cylinder at the start, as well as that used for washing out the sieve and the gauze trap. The messenger sent down to detach and open the machine occupied 21 seconds in reaching the (50 fathoms) point to which the cylinder was attached, and the cylinder then occupied 30 seconds in passing to the stop at 100 fathoms. On examining the sieves, it was found that the more common surface things, Calanus, Sagitta, An- nelid larvee, Hydroid Medusze, and Squillze embryos, were entirely want- ing, and there were only two Radiolarians of the same species as those from the upper levels found after a careful scrutiny of the water. Noth- ing additional was brought up. The cylinder was then sent down a third time, lowered to a depth of 100 fathoms, the messenger sent down to open it (time occupied 45”), and the cylinder travelled from 100 to 150 fathoms (time 45”), so as to collect the animal life to be obtained MUSEUM OF COMPARATIVE ZOOLOGY. 153 between these limits. On drawing up the cylinder and washing out the sieve of the trap, not only did we find that the water contained nothing different from what had been brought up by the cylinder from the lesser depth, but it did not contain even a single Radiolarian. On the 15th of July, in Lat. 34° 28’ 25” N., Lon. 75° 22/ 50” W., we tried the Sigsbee cylinder for a third time, in a depth of 1,632 ‘fathoms. With the same precautions before and after using it, the cylin- der was sent to collect first between 5 and, 50 fathoms (time 30”). The surface was somewhat ruffled, and but little was found on the surface beyond a few Crustacean larvae and Heteropods. The cylinder con- tained Hydroids, fragments of Siphonophores, pelagic Algz, Crustacean larvee, and Heteropod eggs; forms which differed from these scooped at the surface, but were identical with the species found on previous days at the surface under more favorable surface conditions of the sea. Next, the cylinder was arranged to collect between 50 and 100 fathoms (time of messenger 21” from surface to 50 fathoms, time of cylinder 40” to stopper from 50 to 100 fathoms). The water was found to con- tain only a couple of Squillez larvee, similar to those fished up at the surface. The third time the cylinder went down at this station it was lowered to collect from 100 to 150 fathoms (time of messenger from surface to 100 fathoms 45”, time of cylinder in passing from 100 to 150 fathoms 45”). The water when examined contained nothing. No Radiolarians were found at this station, either at the surface or at any depth to which the cylinder was sent (150 fathoms). The above experiments appear to prove conclusively that the surface fauna of the sea is really limited to a comparatively narrow belt in depth, and that there is no intermediate belt, so to speak, of animal life, between those living on the bottom, or close to it, and the surface pelagic fauna. The experiments of using the tow-net at great depths (of 500 and 1,000 fathoms), as was done by Mr. Murray on the “Challenger,” were not conclusive, as I have already pointed out on a former occasion, while the so-called deep-sea Siphonophore, taken from the sounding line by Dr. Studer on the “Gazelle,” may have come, as I have so often observed in the Caribbean, from any depth. I do not mean, of course, to deny that there are deep-sea Medusz. The habit common to so many of our Acalephs (Tima, Aiquorea, Ptychogena, etc.) of swimming near the bot- tom is well known ; Dactylometra moves near the bottom, and Polyclonia remains during the day turned up with the disk downwards on the mud bottom. I only wish to call attention to the uncertain methods adopted for ascertaining at what depth they live. 154 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. As far as the pelagic fauna is concerned, those who have been in the habit of collecting surface animals know full well that the least ripple will send them below the reach of commotion ; Miiller and Baur were the first to adopt the use of a tow-net sunk below the surface to col- lect pelagic animals when the water was disturbed. It seems natural to presume, as we have found from our experiments with the Sigsbee cylinder, that this surface fauna only sinks out of reach of the disturb- ances of the top, and does not extend downward to any great depth. The dependence of all the pelagic forms upon food which is most abun- dant at the surface, or near it, would naturally keep them where they found it in greatest quantity. Of course, with the death and decomposition of the pelagic forms, they sink to the bottom fast enough to form an important part of the food supply of the deep-sea animals, as can easily be ascertained by ex- amining the intestines of the deep-water Echinoderms. ‘The variety and abundance of the pelagic fauna, and its importance as food for ma- rine animals, are as yet hardly realized. One must have sailed through miles of Salpz with the associated Crustacean, Annelid, and Mollusk larve, the Acalephs, especially the oceanic Siphonophores, the Pteropods and Heteropods, with the Radio- larians, Globigerine, and Algz, to form some idea how rich a field still remains to be explored. The variety of the pelagic fauna in the course of the Gulf Stream is probably not surpassed by that of any other part of the ocean. Newrort, R. 1., August 20, 1880. zs No. 9. — Reports of the Results of Dredging, under the Supervision of ALEXANDER AGASSIZ, on the Hast Coast of the United States, by the U. S. Coast Survey Steamer “ Blake,” Commander J. R. Bart- LETT, U. S. WV. VAL Description of a Gravitating Trap for obtaining Specimens of Animal Life from Intermedial Ocean-Depths. By Linut.-Commanper C. D. SicsBes, A eg THE old practice of dragging for animal forms at intermedial depths by means of a tow-net, which, during the several operations of lowering, dragging, and hauling back remained open, was not regarded by Pro- fessor Alexander Agassiz as affording acceptable evidence of the habitat of such specimens as were obtained, and he frequently referred to the subject during our association on board the “ Blake” in 1878. In March, 1880, it having been arranged that Professor Agassiz should make another cruise on board the “ Blake,” Commander J. R. Bartlett, U.S. N., commanding, he asked my co-operation in devising an apparatus to meet the rigid demands of the work in question. This resulted in the apparatus described herein, which is presented in the precise form used with success by the “ Blake,” although, as may readily be seen, it is open to great improvement, especially in minor details. The “ Challenger ” had examined intermediate depths by means of tow- nets trailing from the dredge-rope while hauling the dredge or trawl. In such a practice it must, have been that the depths to which the nets were sunk depended in some degree on the amount of slack rope payed out, and also on the strain upon the dredge-rope due to the resistance en- countered by the dredge when dragging ; it cannot therefore be said that strictly determinate depths were examined by that method, even assum- ing that the nets gathered nothing while being lowered and hauled back. It occurred to me that by using an apparatus in connection with a line and lead, payed out vertically as in sounding, and by dragging ver- tically, instead of horizontally as formerly, there would be at least as much certainty with regard to depths as in the old method, and that simple mechanical devices could be invented to satisfy the conditions of VOL. VI. —NO. 9. 156 BULLETIN OF THE the work. The scheme has been stated in my volume on “ Deep-Sea Sounding and Dredging,” (p. 145, foot-note,) as follows :— “Our plan is to trap the specimens by giving to a cylinder, covered with gauze at the upper end and having a flap valve at the lower end, a rapid vertical descent between any two depths, as may be desired ; the valve during such descent to keep open, but to remain closed dur- ing the processes of lowering and hauling back with the rope. An idea of what it is intended to effect may be stated briefly thus :— Specimens are to be obtained between the intermediate depths a and 6. The for- mer being the uppermost. With the apparatus in position, there-is at a the cylinder suspended from a friction clamp in such a way that the weight of the cylinder and its frame keeps the valve closed ; at 6 there is a friction buffer. Lverything being ready, a small weight or messenger is sent down, which on striking the clamp disengages the latter and also the cylinder, when messenger, clamp, and cylinder descend by their own weight to 6, with the valve open during the passage. When the cylinder- frame strikes the buffer at b, the valve is thereupon closed, and it is kept closed thereafter by the weight of the messenger, clamp, and cylinder. The friction buffer, which is four inches long, may be regulated on board to give as many feet of cushioning as desired.” The following detailed description refers to the accompanying plate. The copper cylinder A, riveted to the wrought-iron frame B, has a flap or clapper valve, C, opening inwards and fastened to the inner arms of the lever D D, the latter pivoting at E. The upper end of the cylin- der is covered with the removable wire sieve F (60 wires to the inch), and inside the cylinder are the wire sieve G (27 wires to the inch) and the wire funnel or trap H (27 wires to the inch). The steel wire rope on which the cylinder travels is placed in the loops II, at the upper and lower extremities of the frame, and is re- tained therein by the screw-bolts J J. The friction clamp is composed of the frame K, the two sliding chocks L and M, the adjusting screw N, the guide screws O O, and the eccen- tric tumbler P. : The friction buffer is composed of the frame Q, the two sliding chocks R and §, the adjusting screw T, the steel compression spring U, work- ing in a chamber, and the regulating screw V. The bearing faces of the two sliding chocks are corrugated, and the inward movement of each chock is limited by a stud forming part of the frame and fitting loosely within a slot in the chock. In clamping the buffer to the rope, the chock R is always screwed in until stopped by its stud; the steel rope MUSEUM OF COMPARATIVE ZOOLOGY. 157 is therefore always pressed between the two chocks by the elastic force of the spring, which may be regulated as desired. To regulate the buf- fer for any definite frictional resistance, clamp it to the rope, and move the regulating screw V well inwards; then suspend from the buffer a weight equal to the resistance decided upon. Move the regulating screw outwards until the buffer slides down the rope under the influence of the suspended weight. Since the chock R is always screwed “ home” in clamping to the rope, the buffer remains regulated for prolonged use with the same resistance ; and, if the latter prove satisfactory, it is probable that the regulating screw need not be touched again for a whole cruise, if the buffer be rinsed in lye-water each time after use. A crank or key, W, is fitted to the squared heads of the regulating and adjusting screws, on which it locks with a spring snap, the latter being operated by the bent arm at one end of the crank. The stud at the other end of the crank is for adjusting the screws J J. The cast-iron messenger, X, is in two parts, connecting with each other by a dovetail, — or something of similar purpose. Professor Agassiz and Commander Bartlett added the funnel-shaped trap, and also the leather cushion, Y, around the valve seat, after a pre- liminary trial with the apparatus. ‘Working the Apparatus. It is necessary to first regulate the buffer to cushion the stoppage of the falling weights, which are, cylinder and frame 38 lbs., clamp 4 lbs., messenger 8 lbs., total 50lbs. The “ Blake” adopted a resistance of about 80 lbs. (this resistance being, of course, constant during the whole movement of the buffer), it having been found that a blow of that force resulted in no injury to the apparatus. On the ascent the buffer must withstand, not only the weight of the fifty pounds of metal, but also the resistance which the water offers to the passage through it of the several parts of the apparatus. Moreover, when the cylinder emerges from the water, it is full of that liquid, and with this increased weight would overcome the stated resistance of the buffer, and force the latter downwards until the lead was reached. To meet these conditions it was not thought advisable to increase the re- sistance of the buffer, which would involve a heavier blow against the apparatus, but a rope-yarn seizing or stop was placed on the rope about fifteen or twenty feet below the buffer, beyond which the latter could not pass. Having secured the buffer to the rope about five or six fathoms above 158 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. the lead (a very heavy lead to keep the steel rope straight) and payed out the length of rope required to span the stratum to be explored by the cylinder, the clamp and cylinder are attached, the latter being suspended from the former as follows. The rope having been placed between the two sliding chocks of the clamp, the arm of the eccentric tumbler is thrown up, which moves the chock M inwards; then, by means of the adjusting screw, the chock L is pressed against the rope, securing the clamp in position. The cylinder hangs four or five inches below the clamp and is supported by a loop of soft wire which rests on the lip of the tumbler; the ends of the wire, being rove through holes in the upper part of the frame of the cylinder, are fastened permanently to the outer arms of the lever to which the valve is screwed. It is seen that by this method of suspension the weight of the cylinder and its frame is used to keep the valve closed while paying out.* The cylinder should be filled with water, poured down through the upper sieve, to maintain the valve on its seat while the cylinder is being immersed. Rope is then payed out slowly until the cylinder is at the desired depth, when the rope is stoppered, and the messenger sent down. | The messenger strikes the arm of the eccentric tumbler, throwing it down and tripping the cylinder. The tumbler in falling relieves the pressure on the sliding chock M, which is then free to recede from the rope. Messenger, clamp, and cylinder fall together, the valve being held open by the resistance of the water. A current is established through the cylinder, and specimens which enter are retained by the upper sieve. When the buffer is reached, the valve is closed by the pressure against the outer arms of the lever. A very slight pressure on the adjusting screw of the clamp, after the chocks are bearing against the rope, is enough to prevent the clamp from slipping, but by an increased pressure on the screw a greater force is required to trip the tumbler, and by this feature the arm of the tum- bler is utilized to break the force of the blow which the body of the clamp receives from the falling messenger. A few rings of sheet-lead may be laid on top of the clamp and the buffer respectively. WasuHiIncTon, D. C., September, 1880. * It is suggested that, in lieu of the soft wire sling, the friction clamp be constructed to receive the end of a stiff wire rod, proceeding from the ends of the lever D D, and that it be done in such a way that, when the valve is closed and the rod connected with the clamp, the bottom of the latter will be in firm contact with the upper part of the cylinder frame. Such an arrangement would effectually guard against the open- ing of the valve with any rapidity of descent. LM Ze | a S . | SSSSSSSSSSSSS ISSSSSSSSSSSSSSSSSSSSSS SSS eR SSSSSSSS SSS3 | © Beso SSsS Ss | Nye eo c-7 wx res 2 < AR aly g ® Gravitating ‘Trap for obtaining Animal farms from Intermedial Oceanllepths . Invented dy €. 2D. Sigshee Lieet. Corndr: USN, with tm provements s ° y S > § & S t Vv g 8 3 & ; & g s s > ( ings ag Paes i q " — es SNL —— E ces oan ay MN Tot “ orrereraces (earemaee ee No. 10.— On some Points in the Structure of the Embryonic Zoéa. By WALTER FAXOoN. TuE embryonic cuticle which clothes the larvee of the higher Crusta- cea at the time when they leave the egg has been studied with more or less care by Du Cane,* Spence Bate,f Fritz Miiller,t Gerbe,§ A. Dohrn,|| Stuxberg,f Claus,** and P. Mayer.tf Miiller first called attention to the fact that the tail of this embryonic skin in certain genera of Brachy- ura (Acheus, Maia) resembles that of the larvee of shrimps and prawns, and working upon this hint Mayer has shown the great morphological and phylogenetic value of a careful comparison of the caudal fin of the embryo with that of the following free-swimming stage. While in Mr. Agassiz’s laboratory at Newport, R. I., in the summer of 1879, I made some observations upon the youngest larval stages of a few Brachyura, especially Carcinus menas and Panopeus Sayi. Although the former species is the subject of Spence Bate’s elaborate memoir on the development of Decapod Crustacea, I am induced to publish my ob- servations on account of the important discrepancies between them and those of Bate. Carcinus meenas.}{ The young of this species are peculiarly favorable for a study of the embryonic membrane, since it is often retained for twenty-four hours after emerging from the egg. In most species, on the contrary, the first moult takes place within an hour or so after hatching ; indeed, in the case of Gelasimus pugnax Smith, which I raised from the egg for the ex- press purpose of examining the embryonic cuticle, I have only succeeded * Ann. Nat. Hist., Vol. III. p. 488, Pl. XI. 1839. + Phil. Trans. Roy. Soc. London, Vol. CXLVIII. p. 589, Pl. XL. 1859. ¢ Fir Darwin, 1864. Eng. Trans. by W. S. Dallas, p. 53. 1869. § Comptes Rendus, Vol. LIX. p. 1102. 1864. | Zeitschr. Wiss. Zool., Vol. XX. p. 621, Pl. XXX. 1870. J Ofvers. Kongl. Vetensk.-Akad. Forhandl., XXX. (1873), No. 9, p. 6. 1874. ** Untersuchungen zur Erforschung der Genealogischen Grundlage des Crusta- ceen-Systems, p. 62, Pl. X. Fig. 9. 1876. tt Jenaische Zeitschr., Vol. XI., p. 246, Pl. XV. 1877. tt It may not be superfluous to append a list of those who have treated of the de- velopment of this commion and widely distributed crab : — VOL. VI.— NO. 10. 160 BULLETIN OF THE in obtaining it by extracting the embryo prematurely from the egg. In this case escape from the egg and the first moult appear to take place simultaneously. The bursting of the egg-membranes is effected by the convulsive at- tempts of the imprisoned embryo to extend its abdomen, which is closely applied to the sternum within the egg. The forked tail first extricates itself (Pl. I. Fig. 1), the antennz then protrude through the breach thus made (Pl. I. Fig. 2), and in a very short time the contortioris of the ani- mal have completely torn away the egg envelope. The embryo, swathed in a delicate, perfectly transparent cuticle, now lies on the bottom of the aquarium supinely awaiting its first moult. It is as yet incapable of swimming about and taking food, its only movements consisting of ex- tension and flexion of the abdomen. It is not until the veil is cast off that the animal loses its embryonic character, and assumes the part of an active, free-swimming larva, with mouth parts adapted for seizing prey. On issuing from the egg, the young measures } mm. in length (Pl. I. Fig. 3). Within the transparent cuticle the zoéa may be distinctly seen as it will emerge on the first moult. The cuticle is not conformable to the underlying larval integument, as it has neither dorsal nor frontal horns, and the antenne and tail are very different. The carapace does not at first extend far enough back to cover the base of the swimming- feet, so that the abdomen appears much longer relatively than it does a short time after hatching. At the joints between the segments of the abdomen of the zoéa the cuticle does not follow the indentations, but otherwise rests conformably upon it. The two prongs of the forked tail of the zoéa are compressed into a very small space by means of a complex folding produced by an invagination of the middle third of the prongs, which does not involve J. V. TuHompson, Phil. Trans., 1835, p. 359, Pl. V. Henrich RATHKE, Zur Morphologie, p. 97. 1837. C. Du Cang, Ann. Nat. Hist., Vol. III. p. 438, Pl. XI. 1839. H. D. 8. Goopsir, Edinburgh New Phil. Jour., Vol. XXXIII. p. 181, Pl. II. 1842. M. P. Erp, Entwicklung des Hummereies, p. 27, Pl. II. 1848. R. Q. Coucn, “Ann. Rep. and Trans. Roy. Cornwall Polytechnic Soc. for 1843.” (I have not seen this memoir. Some account of it is given in Bell’s History of the British Stalk-eyed Crustacea, Introduction, pp. xlix. -liv., Figs. ¢, d, e, and pp. 79-81. 1853.) C. Spence Bats, Phil. Trans., Vol. CXLVIII. p. 589, Pl. XL.-KLVI. 1859. V. HeNsEN, Zeitschr. Wiss. Zool., Vol. XIII. pp. 340, 362, Pl. XX. Fig. 25. 1863. (Auditory organ of the young.) ANTON StuxBeERG, Ofvers. Kongl. Vetensk.-Akad. Forhandl., XXX. (1873), No. Rpt. 1874." ee Fe ae MUSEUM OF COMPARATIVE ZOOLOGY. Lek the distal third which lies within the invaginated portion like a sword within its sheath. The same thing is seen in the spines which are found on each border of the caudal prongs (Pl. I. Figs. 6, 7,12).* The tail of the embryo has an entirely different form. Each half of the fork is pro- duced into seven long spines (Pl. I. Fig. 7). Of these, the three inner correspond to the three internal spines on the tail of the zoéa (PI. IL. ‘Fig. 2). The fourth is the homologue of the prong itself, while the fifth, sixth, and seventh answer to the three minute ones (PI. II. Figs. 2, 5, 6, 7), which are situated on the outer side of the fork. Curiously enough, the spines of the two stages tend to an inverse proportion, the fourth, or smallest in the embryo, being homologous with the prong of the zoéa tail, while the fifth, or largest, is replaced by one of the small external spines (5’) in the subsequent stage. The fourth and seventh are naked ; the rest are fringed with delicate hairs. In a few instances I found the spines of the embryonic skin invaginated in the way already described in the case of the spines of the caudal fin of the zoéa. In one example this invagination affected the second, third, and fifth spines (counting from the inside), (Pl. I. Fig. 6,) in another the third and fifth, in an- other the third only. Without doubt all the longer spines are thus invaginated within the ege.f The two pairs of antennez of the embryo, again, have a much greater deveiopment than in the zoéa, exceeding in length the swimming-feet, and reaching, when stretched backwards, beyond the base of the abdo- men (PI. I. Fig. 3). The first pair (Pl. I. Fig. 4) consists of a basal seg- ment, within which lies the antennule of the zoéa, and which bears two branches, viz. a long one furnished with three longitudinal rows of fine setze, and a very short one. The second antenne (PI. I. Fig. 5) divide a short distance from the base into two branches, one of which has the form of a simple, blunt, fin- ger-like process (a) ; the other divides again into three branches (1, 2, 3), which are fringed with delicate hairs. In some specimens, at the mo- ment of issuing from the egg, one or more of these branches is in- folded like an inverted glove-finger. The short and blunt process (a) encloses the spinous process (Spence Bate) of the antenna of the zcéa, while the triple branch (+), which forms the bulk of the antenna of the embryo, has its homologue in the external branch, or scale (squamiform * According to Milne Edwards, the hairs of the new test of adult crabs which are about to moult are invaginated in a similar way. (Histoire Naturelle des Crustacés, Vol. I. p. 55. 1834.) t Cf. Goodsir, op. cit., Pl. III. Fig. 17; Claus, op. cit., Pl. X. Fig, 9. 162 BULLETIN OF THE appendage of Spence Bate), of the enclosed zoéa. The flagellum of the antenna of the adult, seen in the first zoéa stage as a small protuberance (Pl. I. Fig. 10, c), has no representative in the embryonic antenna. The spinous process and scale of the zoéa antenna are much shortened by invagination, like the structures of the tail already described.* Morphology of the Antenne.—One can hardly avoid the conclusion that, in the same way that the seven-spined forked tail of the embryo is a reminiscence of the Gabelschwantz (P. Mayer) of the primitive Deca- pod, so the greatly developed, setiferous antenne are an inheritance ~ from ancestors in which these appendages subserved locomotive func- tions, as in the Vauplius. The typical second antenna of the Zoéa con- sists of a basal stem produced at its distal end into a long serrate spine (Pl. I. Fig. 10,a; Pl. Il. Fig. 3, i. a), and bearing besides an articulated squamiform appendage (>). The spine is seen in a rudimentary form in the larvee of the shrimps, prawns, and Paguride. The squamiform ap- pendage is homologous with the external branch of the second antenna of the larval Macroura, and with the antennal “scale” of the adult Macroura. Both the spinous process and the squamiform appendage become aborted in the development of the Brachyura. The flagellum of the second pair of antennee of the adult crab is wanting in the youngest _zoéa stages, or is represented by a small papilla merely (c). If the relation of the embryonic antenna to the Vauplius antenna, suggested above, be correct, it follows that the bulk of the antenna of the Nauplius is not represented by any homologous part in the perma- nent antenna of the crab. If, on the contrary, it be claimed that the large fringed lobes of the embryonic antenne simply represent antennal sete, they still point back to a primitive condition in which the first two pairs of appendages were provided with Schwimborsten, and served as natatory organs. . The labrum, mandibles, metastoma, and maxille have nearly the same form which they have in the zoéa stage which follows. The long swim- ming-setze of the first and second maxillipeds, which play so conspicuous -a, part in the life of the zoéa, are very much shortened by invagination, and entirely covered by the embryonic cuticle. The third pair of maxillipeds and the two following pairs of appendages of the zoéa show through the transparent membrane as three pairs of small buds (PI. I. Fig. 3, viii., ix., x.), but there are no corresponding structures in the embryo. * A. Dohrn, who observed similarly formed antenne in the embryo of a species of Portunus (1. c.), has confounded the two pairs. a alee MUSEUM OF COMPARATIVE ZOOLOGY. 163 The young remains in this embryonic condition for about twenty-four hours (at least in confinement). In the mean while it has increased in size to such a degree that the delicate investing membrane is no longer ample enough for the enclosed zoéa and the first exuviation takes place. The cuticle of the abdomen is cast first, commonly coming off in one piece (Pl. I. Fig. 9, 9’). The dorsal spine, which has been invaginated like the parts already described, and laid forward over the back, begins to be evaginated, and to erect itself, and thus aids in splitting the mem- brane along the back. The rostrum, which has been applied to the breast, also emerges, and the abdomen, freed from the embryonic cuti- cle, is now used to clear the appendages of the cephalo-thorax, in this wise : the ends of the two prongs of the tail-fork are bent so as to form minute hooks (Pl. I. Fig. 12): when the abdomen is flexed, these little hooks catch in the membrane covering the cephalo-thoracic appendages, and on extending the abdomen again the membrane is torn off (Pl. IL. Fig. 9). | The dorsal horn is commonly evaginated, and assumes its position with a slight backward curve even before the embryonic skin is entirely got rid of. In specimens which have just cast the embryonic skin, a break in the trend of the spine indicates the rim of the former invagi- nation (Pl. I. Fig. 14). The rostral spine now projects downward at a | right angle with the long axis of the body. The sets on the various parts of the body unroll themselves, the mouth parts become functional jaws, enabling the young animal to feed; the two pairs of swimming- feet, provided each with four long swimming-sete on their external branches, become active agents for locomotion, and now, in place of the inert and pupa-like embryo, we have a vigorous free-swimming larva. Besides the great difference between the two stages caused by the sudden development of the dorsal and frontal spines, the two pairs of antennze and the tail have an entirely different form. Both pairs of antenne are now of relatively small size. Those of the first pair are composed of but one segment, which carries three long sensory threads at the tip. This segment corresponds to the basal segment of the first antenna of the embryonic stage. The second pair of antennz consist of a basal piece with a long ser- rate spinous process (Pl. I. Fig. 10, a; Pl. II. Fig. 3, a), which lies in the short, blunt process of the antenna of the embryonic stage (PI. I. Fig. 5, a), and a short, blunt protuberance (PI. I. Fig. 10, ¢), the rudi- ment of the antenna of the adult crab. In addition to these processes, there is articulated to the basal piece 164 BULLETIN OF THE a long joint with a long and a short hair on its extremity (Pl. I. Fig. 10, 6; Pl. Il. Fig. 3, b). This is the homologue of the “scale” of the antenna in Macroura, and appears to represent the main, triple portion of the embryonic antenna (Pl. I. Fig. 10, 6). The tail (Pl. I. Fig. 2) has now the form so characteristic of the zoéa of Brachyura. It is a forked piece, each prong of the fork bearing three setze on the inner side near the base, and three minute ones on the outer side. ‘The prongs of this forked tail themselves are homologous with the fourth spine of the embryo tail, as before pointed out. The outer three (5, 6, 7) diminish in size successively. Although I succeeded in keeping some of these zoée alive for seven days, none passed through another moult. In Spence Bate’s classic memoir on the development of Carcinus me- nas, the embryonic membrane which covers the zoéa when it first quits the egg is described and figured as conformable to the whole animal, the tail and antenne not excepted. Thus are ignored the most inter- esting and suggestive structural features of the embryo. This error of observation is the more remarkable, since the structures in question were figured with approximate accuracy twenty years before by that close observer, Captain Du Cane.* H. D. 8. Goodsirf also seems to have seen the same structures, al- though his description and figures are very incorrect. The “curious brush-shaped appendages of the embryo,” which ‘drop off when the animal has escaped from the ovum, and are replaced by spines,” { are evi- dently the invaginated caudal spines of the embryonic cuticle, such as are represented in our Plate I. Fig. 6. Spence Bate’s identification of the two pairs of swimming-feet of the zoéa with the second and third pairs of maxillipeds of the adult, instead of with the first and second pairs, was not so strange; but why does he persist in the old error, even in his latest papers,§ after it has been particularly pointed out by Fritz Miiller,|| Stuxberg,{ Claus,** and others ? * Op. cit., Pl. XI. Figs. 1, 5. + Edinburgh New Philosoph. Jour., Vol. XXXIII. p. 182, Pl. III. Figs. 16, 17. f 1842. | + Pps 382;.191,,Pli ILL Bignl7: | § Report on the Present State of our Knowledge of the Crustacea. Rep. Brit. i Assoc. Adv. Sci., 1875, p. 48 ; 1876, p. 89 ; 1877, p. 44; 1878, pp. 7, 8. | Op. cit., Eng. Trans., p. 52. ia J Op. cit., p. 10. . ** Wiirzb. naturw. Zeitschr., 1861, p. 30. Untersuchungen zur Erforschung der Genealogischen Grundlage des Crustaceen-Systems, p. 62. 1876. MUSEUM OF COMPARATIVE ZOOLOGY. 165 Panopeus Sayi. The remarkable zoéa represented on Plate II. Fig. 4, a very common form on the southern shore of New England, I raised from the eges of Panopeus Sayt in the summer of 1876. It differs strikingly from all other zoée with which I am acquainted in the structure of the second pair of antenne (1.), which consist of a single monstrously developed spine equal in length to the rostrum. In other regards the zoéa is not specially noteworthy. The carapace has, in addition to the rostral and dorsal spines, a pair of short lateral spines. In the middle line of the back, well forward toward the eyes, is a well-marked hump. The caudal fork (Fig. 5) bears but four pairs of spines; the two exte- rior pairs (6 and 7 in Carcinus) are wholly wanting. To which part of the typical second antenna of the zoéa, as described on page 162, does the long, rod-like antenna in this species correspond ? In order to answer this question we must examine the cuticle of the embryo. This is represented by Fig. 8 of the plate. It has a form similar to that previously described in Carcinus menas (PI. I. Fig. 5) ; but here the branch marked 3 is split nearly to the base, making an ap- parently quadruple structure in place of the. triple branch of Carcinus. The blunt, finger-like process (a) encloses the antenna of the zoéa (a’), which is marvellously shortened by evagination. The homology of the zoéa antenna in this case is thus fixed. It represents the spine of the normal antenna. The cuticle covering the first pair of antenne (Fig. 7) has the same parts as the corresponding structure in Carcinus, and the same with the tail (Fig. 6), in which the two external spines (6 and 7), which are en- tirely wanting in the first stage of the zoéa, are well developed. CAMBRIDGE, July, 1880. 166 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. EXPLANATION OF THE PLATES. PLATE I. Carcinus mzenas. Fig. 1. Embryo beginning to emerge from the egg. Fig. 2. The same, a little further along. Fig. 38. Embryo shortly after hatching. Fig. 4. First antenna of the same. Fig. 5. Second antenna of the same. The branch (3) invaginated: a/, spine of the antenna of the zoéa seen through the cuticle ; 6/, squamiform: ap- pendage of the antenna of the zoéa. ; Fig. 6. ‘Tail of the same: the enclosed tail of the zoéa is shaded ; spines 2, 3, and 5 are invaginated. 7. The same : all the spines of the embryonic tail evaginated. Fig. 8. Invaginated rostrum of the zoéa, as seen through the embryonic cuticle. 9. Young in the act of exuviating the embryonic cuticle. Fig. 9/. The cuticle of the abdomen, just cast from Fig. 9. Fig. 10. Second antenna of the zoéa: a, spine; b, squamiform appendage ; ¢, rudi- ment of the flagellum of the adult. The spine and squamiform append- age are still invaginated. Fig. 11. To show the way the dorsal spine lies at the time of the first moult. It has become evaginated, but not yet erected. Fig. 12. Extremity of a prong of the caudal fork, to show the unfolding of the dis- tal part, and the terminal hook. Fig. 18. Rostrum and antenne of a zoéa at the moment of exuviating the embry- onic cuticle. Fig. 14. Dorsal spine of zoéa immediately after casting the embryo skin. The break near the middle of the spine shows the rim of the invagination during the earlier period. POATE Wt: Figs. 1-3. Carcinus mezenas. Fig. 1. First stage of the zoéa. The appendages are marked by consecutive Roman numerals. Fig. 2. Tail of the same. Fig. 38. First and second antenne of the same. Figs. 4-10. Panopeus Sayi. Fig. 4. First stage of the zoéa. Fig. 5. The same, viewed from behind. Fig. 6. Tail, with the embryonic cuticle. Fig. 7. First antenna of the embryo. Fig. 8. Second antenna of the embryo: a/, antenna of the zoéa seen through the embryonic antenna. Fig. 9. Second maxilla of embryo. The shaded part represents the appendage of the zoéa within. Fig. 10. End of swimming-branch of first maxilliped. The long swimming-sete are shortened by invagination and closely invested by the embryonic cuticle. Fig. 11. Tail of Gelasimus pugnaxz, Smith, first stage of the zoéa. Spines 5, 6, 7, are entirely wanting. : No. 11.—WNew Species of Selachians in the Museum Collection. By SAMUEL GARMAN. Scyllium ventriosum n. sp. Bopy very stout in the anterior half, hinder portion slender. Head flattened, as broad aslong. Snout short, blunt. Eyes medium. Spiracle small. Nostrils near the mouth, separated by a space equal to the length of the snout, with a valve on each side. Anterior nasal valve short, broad, more than half as wide as the nostril, reaching the teeth ; posterior smaller, of similar shape and hidden by the first. The distance of the valves from each other is equal to three fourths of the length of the snout. Mouth wide, crescent-shaped. Labial folds rudi- mentary, not visible when the mouth is closed. Teeth small, central cusp long - and slender, with two lateral cusps on each side, the outer of which is feebly developed, in fifty-four rows in the upper jaw. The symphysis bears no teeth; on each side of it the first two rows are very small. Gill openings narrow, the - fourth and fifth over the pectoral, the third twice the width of the fifth. Pec- torals broad and short; margins convex, the anterior one fourth longer than the posterior; angles rounded. Ventrals short, margins convex, outer ex- _ tremity broadly curved, posterior blunted. First dorsal twice the size of the : second, base above the posterior half of the ventral, height little less than the length of the base, borders convex, upper extremity round, posterior blunt. Second dorsal smaller than the anal, distant from the first the length of the _ posterior border, its entire length less than that of the base of the anal, upper id border curved, posterior straight, hinder angle acute. Tail less than a fourth of the total, its width contained in its length two and a half times, notched near the extremity on the lower side, no pit at the root. The shape of the tail is similar to that of S. stellare or S. canicula, though broader than that of either. Scales pedicellate, sharp and coarse. Nine circuits in the spiral of the intestine. Color grayish brown, spotted and banded with darker. The spots are in- distinctly outlined, irregular in size and position. Bands transverse, twelve or more in number ; five of them occur between the eyes and first dorsal. Lower surface darker, olivaceous and more uniform. The specimen, an adult female, is twenty-nine inches in length, and measures fifteen inches around the body between dorsal and pectorals. This species differs from S. chilense in the nasal valves, labial folds, lateral cusps on the teeth, small second dorsal and its position with respect to the anal, and the numerous transverse bands. One specimen from Valparaiso. VOL. VI.—wNo. 11. 168 BULLETIN OF THE Rhinobatus lentiginosus n. sp. Outlines of body and fins similar to those of Horkelit and wndulatus. Ros- tral cartilage long and narrow, a small groove near the head; ridges close together from base to extremity. Eyes large. Spiracles half as large as the eyes, with two folds. Head narrow, concave between the eyes. The width of the interocular space equals that of the nostrils or their distance apart. Half the length of the snout is less than the distance between the outer angles of the nostrils. Mouth nearly straight, a little less than twice the width of the head between the eyes. Scales small, smooth. Spines of the dorsal series and the three in front of each eye very small ; those above the eye and spiracle not noticeable. No larger spines on shoulders or rostrum. The largest spines on the body are a group of five on the top of the end of the snout. Color a light grayish-brown freckled with small spots of lighter ; uniform brownish below. On the lower side of the snout there are faint indications of markings similar to those of wndulatus. Distinguished from Horkelit and undulatus by the colors, the horn-like spines on the end of the snout, the absence of spines on the shoulders, the narrowness of the head as compared with the width of the mouth, the shorter distance from snout to mouth, and the greater distance from mouth to vent. Total length 22.9, snout to mouth 4.1., snout to vent 9.9, and width of pectorals 7.4 inches. An adult female secured in Florida by Prof. L. Agassiz. Rhinobatus planiceps n. sp. Disk, including ventrals, rhombic, about one and a half times as long as wide. Anterior borders of pectorals straight, more than twice as long as the convex posterior margins. Angles of pectorals rounded, the hinder not extend- ing farther than to the vent. Outer angle of ventrals rounded, posterior acute. Head broad, flat. Rostral cartilage medium, dilated at the extremity, with the ridges close together in the anterior third of their length. Snout rather broad, with rounded extremity. Eyes moderate. Spiracle immediately behind the eye, smaller than the orbit, with a single fold on the posterior side. Anterior nasal valve not dilated ; posterior two-lobed. Mouth nearly straight. Body covered with shagreen above and below. Tail much depressed, with a fold on each side. Second dorsal distant from the caudal the length of its base. Bases of the dorsals distant from each other the length of the anterior borders. Scales larger over the central portions of the disk. Compressed hooked spines in a median row on back and tail, in two patches on each shoulder, and a series above each eye. On the young these spines are much more prominent and regular in size than on the adult. Color brown, light between and on each side of the rostral ridges ; white below. Young specimens with a number of small round white spots on each side of the dorsum. The following measurements are taken from a young male : — MUSEUM OF COMPARATIVE ZOOLOGY. 169 Total length . . oi AW ae eT © FEO inehes: Snout to end of ventrals Ai es sf emake a tk Pai OL SEERERIGCHILY Fe ete ure My Sey me Oe & Sere COMOUG SHI) Pou i be ah a oe) pee Width of pectorals . . . .. ay! Paty Gath pe ORGS Twenty-one specimens from Payta, Callao, eA Galapagos Islands, collected by the Hassler Expedition. Trigonorhina alveata n. sp. Disk, including the ventrals, rhombic, longer than wide. Anterior borders of pectorals nearly straight ; posterior convex. Snout truncated, as wide on the end as the space between the eyes. Rostral cartilage wide and strong, deeply grooved on its upper surface. Rostral ridges prominent, widely sepa- rated, nearly or quite parallel from base to extremity. Spiracles large, equal in diameter to the orbit, without a fold on the side. Fin angles rounded, with the exception of the obtuse posterior angles of the dorsals. Dorsals elevated, behind the ventrals; the length of the base of the first less than the length of its posterior border; base of the second equal to its posterior margin. The base of the first is equal to its distance from the ventral or the second dorsal. Anterior nasal valves dilated, continued beyond the inner angles of the nostrils, but separated from each other by an interspace ; posterior two-lobed. Anterior extremities of the pectorals widely separated from the rostral cartilage, extend- ing very little in advance of the eyes. Mouth in a low arch, regularly curved from the corners. Teeth small, blunt, in a hundred and ten series in the upper jaw. Claspers long, slender, knobbed at the end. Tail with a thick fold on each side. Caudal fin rounded, without indentation. Back thickly covered with small scales, among which are scattered larger ones. A median row of large blunt tubercles on back and tail, and two short rows parallel to this on each shoulder. The bases of the tubercles are so covered by the skin and small scales that they appear as rounded prominences with a small spine on the summit. Color grayish brown. Near the extremities of the rostral ridges there is a band of dark brown ; between this and another dark band which crosses the bases of the ridges there is a light band. A dark band across the head between the eyes is somewhat confluent with the band in front of it, which makes the fore part of the head dark, but leaves the prominences in front of the eyes light- colored. The remainder of the upper surface is more or less clouded by faint indications of transverse bands. These are probably distinct in the young. With the exception of a dark spot on the posterior angle of each pectoral, the lower surface is white. Total length . . . SAVE TS een ene Bagy® OP. | inches. Snout to end of ventrals ee prce SAC tan Aa RD ONT GEG Peto Of pectoralaity sai. a Oo 2B SIE OCCUR ul uate Md tha ty athe"! tec oryde ROES = Snout to mouth as) cited al aa! oa ay Width of mouth .. ; gat) eat oy Distance between outer angles be Hesttilas ee 170 BULLETIN OF THE Trigonorhina exasperata. This is the species described by Jordan and Gilbert under the name Platy- rhina exasperata, and from which at a later date these authors drew the charac- ters for the genus Zapteryx. The latter does not seem to differ from the genus - Trigonorhina of Miiller and Henle. The species T. exasperata and T. alveata are closely allied. The genus Platyrhina is closely related to Trigonorhina, and with it belongs to the family Rhinobatide. Both genera have broad based tubercles in a verte- bral series and on the shoulders. Sympterygia and Platyrhina have little or no affinity for each other. Of the Rhinobatide the latter is, perhaps, the nearest approach to the Rajw. It is out of place with the Rajide, as located by Du- meril and Giinther. ” Trygon lata n. sp. Disk quadrangular, one fourth wider than long. Anterior margins nearly straight, forming a very blunt angle at the snout, rounded near the outer ex- tremities ; posterior convex; inner straight a portion of their length. Ventrals truncate, rounded. Snout produced, forming a rounded prominence in front of the margins of the disk ; length from forehead less than the width of the head. A line joining the wider portions of the disk passes nearer to the head than to the shoulders. Tail more than twice as long as the body, subcylindri- cal, without a trace of keel above, roughened with small tubercles, with an irregular series of broad-based conical tubercles on each side; a long narrow cutaneous expansion below has its origin opposite that of the spine, and ter- minates in a keel which continues to the extremity. A pair of large com- pressed erect tubercles stand immediately in front of the caudal spine, and a single one is placed over the middle of the pelvic arch ; these suggest a con- tinuous series in larger specimens. Three larger elongated tubercles with points directed backward — similar to those of hastata —oceupy the middle of the shoulder girdle. Mouth curved, six (5-6?) papillze at the bottom ; two of these are in the middle in front where usually there is but one. Color light olive, probably greenish in life, white below. Distinguished from T. centrura by the prominent snout, the shape of the tubercles on the middle of the back, and the narrowness of the posterior portion of the disk. Length of body 16, length of tail 35.3, and width of pectorals 20.5 inches. Collected at the Sandwich Islands by Andrew Garrett. Trygon longa n. sp. Disk quadrangular, about one sixth wider than long. Margins nearly straight, anterior meeting in a blunt angle on the end of the snout. Outer angles rounded, posterior blunt. Ventrals rounded. Tail more than twice as long as the body, roughened with small asperities, depressed anteriorly, com- pressed behind the spine, keeled above the compressed portion, with a long narrow cutaneous expansion on the lower side. Mouth curved, with five ‘MUSEUM OF COMPARATIVE ZOOLOGY. 171 papille. A row of small tubercles behind the head on the shoulder girdle. It is likely that large specimens are provided with tubercles on back and tail. Distinguished from 7’, lata by the shape of the disk and snout, and the keel on the tail ; from 7. centrura by the straight margins of the pectorals and the keel. One specimen secured at Acapulco, Mexico, by Prof. Alex. Agassiz. One light-colored, reddish-brown specimen from Panama, by the Hassler Expedi- tion. Length of body 11.5, length of tail 28, and width of pectorals 13.8 inches. Length of body of second specimen 9.3, length of tail 24.5, and width of pecto- rals 11.2 inches. Trygon brevis n. sp. Disk quadrangular, a little wider than long. Anterior margins nearly straight, curved near the outer extremities to meet the convex posteriors, meet- ing in a blunt angle on the end of the snout. Outer and posterior extremities of pectorals round, without trace of angles. Ventrals broad, truncate, with angles rounded. Tail less than one and a half times the length of the disk, tapering to an acute point, depressed as far as to the spine, thence compressed to the end of the cutaneous fold and round from this point to the end, with a short elevated membranous expansion behind the spine, and a longer and wider one on the lower side extending below the former and the spine. The expan- sions have their hinder extremities opposed ; they end quite abruptly, and are widest near the termination. Mouth with five papilla, outer small. Teeth small, blunt. Upper jaw indented in the middle; lower, with a prominence in front. Disk naked in the young. Adult specimens have three rows of tuber- cles on the middle of the back disposed as are those of T. hustata. A large specimen from Payta has three large, erect, broad-based tubercles in front of the caudal spine, and the tail rough with smaller ones. The short rows on the shoulders contain from one to four, and probably increase in number with age, as is the case with closely allied species from the Atlantic coast. Color olive or grayish brown, reddish near the edges ; below white, with round spots of brownish under the base of the tail. . Compared with hastata this species differs in the shorter tail, the rounder extremities of the disk, and the shape and size of the tubercles and membra- nous fins. T. hastata has no expansion on the top of the tail, and that on the lower side is very long, of moderate width, and tapers gradually. Those of brevis are comparatively short and broad ; they rise gradually and terminate abruptly. From T. Sayz this species is to be distinguished by the great development of the caudal expansions, their shape and length, and by the tubercles on shoul- ders and tail. A large female measured in length of body 17, length of tail 23, and width of pectorals 18 inches ; a young male, length of body 8.1, length of tail 12, width of pectorals 9.2 inches, Including this and the preceding, the number of American species properly belonging to the genus Trygon is increased to seven. 172 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. Trygon brachyurus and T. reticulatus, recently described by Dr. Giinther, belong to the genus Potamotrygon. The species redescribed and figured by Dr. Steindachner in 1878 as Teniura magdalene also belongs to that genus. It needs but a slight knowledge of the anatomical differences existing between the Potamotrygones and the Teniure proper to convince any one that both cannot be retained in the genus Tenwura. CAMBRIDGE, October, 1880. BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE, IN CAMBRIDGE. | VOL: VL. Parr [f.—No. 12. CAMBRIDGE, MASS., U.S. A. 1881. UNIVERSITY PREsS: Joun Wi son AND Son, CAMBRIDGE. CONTENTS. PART if. Binney. By E. L. Mark A. OBSERVATIONS I. Maturation II. Fecundation . III. Segmentation B. BIBLIOGRAPHY I. Limax 1. Egg Papelaness ae 2. The Yolk and its Changes . II. Review of Maturation, Fecundation, and Cell- Division 1. Cell-Division @ Asters. ; b. Quiescent Nuclei c. The Nucleus during Division Introductory a, Segmentation B. Tissues y. Plants 2. Maturation 3. Fecundation . C. THEORETICAL CONSIDERATIONS AND GENERAL CONCLUSIONS Promorphology of the Ovum Polar Phenomena Asters . Spiral Asters Nuclear Spindle . Origin of Nuclei Germinative Vesicle Polar Globules APPENDIX ALPHABETIC LisT OF THE Treen INDEX To AUTHORS CITED IN THE TEXT EXPLANATION OF THE FIGURES PAGE No. 12. — Maturation, Fecundation, and Segmentation of Limax campestris, 173 173 Uy 215 222 232 232 232 235 244 244 245 253 272 272 276 341 366 387 368 512 512 514 519 533 536 539 545 547 558 591 615 617 ’ wal wif om Leet Pa c ‘ 4 a +5 a: us » ie ra P i f etre ; woe a i a ALL See t , oh Matas: < ie ai Pe fi . . : me tae ‘ey ate oo ; 2 iy P in lewwge i 12. — Maturation, Fecundation, and Segmentation of Limax campestris, Binney. By HE. L. Mark.* Tue observations of the past five years ft on the earliest stages in ontogeny have contributed more to the solid advancement of biological knowledge, than those of any corresponding interval since the studies of Max Schultze and others paved the way to a science of Biology. More refined methods of research have resulted in more exact knowl- edge of phenomena. A closer study of details has opened the way to a broader comprehension of their significance. It was with the hope of adding something to the empirical acquisi- tions in this field, that I undertook the studies whose results follow. A. OBSERVATIONS. The eggs of Limax campestris, Binney, are found in moist places, pro- tected from the drying influences of direct sunlight and currents of air. They are frequently met with in the vicinity of a small stream, some stagnant pool, or in low meadow-land. Open woodland presents favor- able conditions for their development, affording sufficient warmth, and preventing too direct sunlight and constant winds. In such locations loose piles of decaying wood are often chosen for the deposit of eggs. At other times, when the ground is less protected, they may be found under loose stones, or even in the bed of some spring-time water chan- nel, where crevices in clumps of earth afford protection. The most of the material which I have studied was obtained from slugs kept in confinement. These were collected from partially shaded ground with Scanty grass-growth, in the vicinity of Fredonia, N. Y. A portion, however, were from low grass-land near the Museum of Comparative Zoblogy in Cambridge. * I desire to acknowledge my indebtedness for the use of books to the extensive libraries connected with the University, as well as to the Boston Society of Natural History, the Boston Public Library, and the Boston Medical Library. I am under obligations to the librarians of all these institutions for personal or official favors, for which I take this opportunity of expressing my thanks. + The unfortunate delays which have attended the publication of this paper are liable to mislead the reader, unless it is borne in mind that it was prepared early in 1879. See a preliminary notice in Zool. Anzeiger, 2 Jahrg., p. 493. VOL. VI.— No. 12. 174 BULLETIN OF THE The eggs are usually found in clusters of about a dozen each, though the number is subject to considerable variation. Sometimes they are only loosely collected together, or even moderately scattered over an area of a few inches; at others, they are closely packed in a more or less rounded mass. Owing to the nature of the place chosen for de- posit, they are often arranged in rows, as in the narrow cracks of moist, decaying wood, or in the chinks in cakes of earth. On splitting the wood or breaking open the earth, they are occasionally found to fill all the available space completely, and if the cavity is broad and shallow they are accordingly arranged in rows a single layer deep. It is won- derful into what narrow crevices the eggs are sometimes crowded, ap- parently for better protection from enemies. They vary in external appearance according to the hygrometric con- ditions in which they are found. If the requisite amount of moisture is available, they are of a full, plump outline, and resemble beads of pearl or frosted silver. If their surroundings are dry, they have a shrivelled look, are more or less flattened, and have a faint yellowish tint. Moisture restores them to their normal shape and color. A careful examination will show some modifications of form, especially if the eggs are taken from different groups. Those taken from a single mass are usually rather uniform in appearance, though they may show noticeable differences. The same is true of their dimensions. The average long diameter is a little more than 2 mm. The short diam- eter may almost equal the long diameter, or it may be hardly more than half as long. Sections of eggs at right angles to the long axis are almost circular, and never differ in any constant manner from that form; but sections coinciding with the long axis would, in most cases, show oval outlines varying, as has been indicated, in the proportions of their axes. The curvature at either end of this oval is usually about the same, al- though in some cases one is more pointed than the other. Furthermore, one end (sometimes both) may be drawn out into a sort of cue, which varies greatly in different eggs. Rarely the cues of a couple are con- tinuous. In those found at Fredonia I have never seen more than two thus united. Usually all are quite separate, even though lying in groups close together. In those found at Cambridge I have observed a greater tendency to this union, and once counted thirty thus joined into a delicate rosary. There could be no doubt in this case that all were laid by the same individual, and in regular succession. Indirect evidence that those contained in a given mass were also all laid at the MUSEUM OF COMPARATIVE ZOOLOGY. 175 same time (i. e. in rapid succession) is usually to be found in the com- parative uniformity in size and shape which the individual eggs of the group present. The greatest number observed which thus indirectly gave evidence of belonging to a single deposit was thirty-seven ; on the other hand, it is quite certain that a very small number may be deposited at one time by slugs that are held in confinement. That the same is true of unconfined animals, I can only infer from finding, now and then, small groups or single eggs far removed from any others. The external surface of the egg is not smooth, but raised in almost inperceptible bosses, which give to it the frosted look mentioned. Im- mersed in water and examined under a low power of the microscope, it is seen to be composed of a central, slightly yellowish, homogene- ous portion, much more nearly spherical than the whole egg, and of two thick coats of investment, which are colorless, and give it rigidity and a great degree of elasticity. The central mass occupies from two thirds to four fifths of the diameter of the whole egg. The two envel- oping layers are not of uniform thickness, and may become af one or both ends exceedingly thin., The outer layer is composed of colorless lamine, which are for the most part nearly concentric, although at intervals they may become thinner and disappear. The cue is formed from this layer alone. There may often be distinguished a half-dozen principal laminz, and also, with a higher magnifying power, secondary laminz of varying thickness, and often in large numbers, The inner layer is likewise colorless and transparent, but shows no trace of lamina- tion.- When the outer layer is cut, it is found to be resistent and elastic; but the inner layer offers less resistance and is rather viscid. The inner layer is separated from the central, yellowish mass by a very firm, structureless membrane, which exhibits a great tendency to wrinkle, especially when moisture is withdrawn from theegg. This firm structure is the membrana albuminis. The contained yellowish substance is viscid, like the white of the hen’s egg, and like it is albuminous. In the freshly laid egg it appears quite homogeneous. It is called the albu- minous envelope, but from its great abundance here its nature as an envelope is not striking. In this substance are suspended two struc- tures which are conspicuous in all freshly laid eggs when examined with a sufficiently high power. One of these is tortuous, and usually ex- tends from near the surface of the albumen to the vicinity of the other structure. It resembles an irregularly twisted, or here and there con- stricted, thin-walled tube. As I hope to make it the object of further study hereafter, I will only add that it has been compared to the chalaza 176 BULLETIN OF THE of the hen’s egg, and will pass to the consideration of the other body, — the vitellus, or egg proper, —to which all the other parts are simply accessories. This vitellus, or yolk, has not more than one twentieth the diameter of the whole egg, and when the latter is freshly laid it appears as a minute speck, 125 yw. in diameter, just visible to the unaided eye as a whitish dot, which usually has an eccentric position. It is to the study of the yolk, and the changes it undergoes, that I shall confine my attention. Some of these changes may be followed in the living egg under the microscope ; other and remarkable changes, which up to within a few years had escaped the attention of embryologists, are meanwhile going on within the yolk, and are either altogether hidden, or are only par- tially visible to one studying the living specimen. It is only by the use of certain acid reagents, which have the immediate effect of killing the ege, and at the same time of hardening it, that these internal conditions may be successfully studied. In considering the successive metamor- phoses which the yolk undergoes, it will perhaps be best to follow the course which the observer is compelled to take; that is, to notice first what may be observed in the living egg, and then to supplement the knowledge thus gained by such instantaneous pictures as the hardening process affords. The more numerous these views, and the more frequent and regular the intervals at which they are taken, the more complete will be the data for interpreting these indirectly observed phenomena. The changes which it is proposed to follow in this paper are only such as occur between the time the eggs are excluded and the end of the first segmentation. Inasmuch as the following observations begin with the deposited egg, —i.e. do not include a study of the ovarian egg, nor of any of the changes it undergoes within the body of the parent, — I cannot claim for them the completeness I wish they possessed. Recent studies on the very early stages of eggs of other animals will, however, enable us to make a better use of these limited observations than could be made otherwise. For the time indicated, I trust they will be found tolerably complete and connected. The nature of the phenomena which transpire within the limits of the time selected ailow one to group the observations about three principal heads : — 1. The changes connected with the ripening of the egg. 2. Fecundation of the mature egg. 3. Segmentation, or cleavage. The observations under the first will be least complete, because they — MUSEUM OF COMPARATIVE ZOOLOGY. 177 commence after a part of these maturation changes have already tran- spired. These three series of events will be treated in the order men- tioned, as that is substantially the order of their occurrence in time ; it should be mentioned, however, that they are not strictly and com- pletely consecutive, for each series of changes is still incomplete at the beginning of the next following, — there is, as it were, an overlapping in time, — and for this reason it will be less advisable to follow the strict chronological, than the physiological order as above indicated. As far as regards what may be observed on the living egg, the very accurate studies of Nicholas Warneck, though made as long ago as 1850, leave very little room for additions. It was some time after my first studies (middle April — middle May, 1877) on Limax were ended before the opportunity was afforded for an examination of the literature on the development of pulmonates, which was entirely inaccessible to me at the time I was making the observa- tions. Among other references in Bronn’s Die Klassen und Ordnungen des Thier-Reichs was that which first directed my attention to this valu- able paper by Warneck, hitherto unknown to me even by title. I was temporarily deterred from publishing my studies by the fact that this observer had already published so truthful and complete an account of the development in the case of a slug very nearly related to the one which had formed the basis of my investigations. There were still some points (more especially in the stages of segmentation, which will fall outside the limits of the present paper) in which my observations were at variance with those of the Russian naturalist. It was in part these matters of disagreement, but more especially the influence of the recent writings of Biitschli, Hertwig, Fol, and others, which determined me, early in 1878, to renew my observations at the first opportunity, and to address particular attention to the phenomena to be observed before _ and during the first segmentation. I was able to devote only a few days to this study in Cambridge, during the latter part of June. The most of the observations were made at Fredonia, in August, 1878. I. MATURATION. In eggs examined directly after their deposit the vitellus appears as a spherical mass of a slightly yellowish or brownish tint, with per- fectly clear, sharp outline, about 0.125 mm. in diameter. It has greater density than the surrounding albumen. Its opacity is occasioned by an immense number of granulations, varying in size. Part of these VOL. VI.— No. 12. 12 178 BULLETIN OF THE promptly swell when, by rupture of the yolk, they are brought into contact with water, and assume spherical contours, with delicate out- lines and diameters varying from 2 to 8 pw. Others remain small and of greater refractive power, under the same circumstances. They sel- dom exceed a fraction of a micro-millimeter (4) in diameter. (Fig. 26.) These granules are held in suspension by a viscid transparent proto- plasm. ‘Their distribution is not always uniform, so that an irregular cloudy appearance often characterizes the yolk. In any optical section the peripheral portions of the sphere, owing to the diminished quantity of these granules which the light is compelled to traverse, seem less opaque than the central portions. A very thin shell of protoplasm at the surface is entirely destitute of granulations, though the yolk is certainly not provided with a distinct membrane, the so-called membrana vitellina. Toward the centre of the sphere the opacity is not, however, ‘a constantly increasing one, for at or near this point there appears an elongated lighter portion, which is not distinctly limited, but shades gradually into the darker surrounding portions. This is caused by the absence of yolk granules from the central part of the vitellus. I have not been fortunate enough to secure an egg in which this central spot was perfectly spherical, as did Warneck; already a lengthening had taken place, and in most cases it appeared as two contiguous lumi- nous areas. These become more extensive in the course of a few min- utes, and soon appear so displaced that one is much nearer the surface of the yolk than at first. It is only in exceptional cases that these light spots can be seen, previous to the time when one of them appears near the surface. The more superficial spot is then the more conspic- uous. As these draw nearer to one side of the yolk, the granules seem gradually to recede from that side toward which the clear bodies are tending, so that a considerable portion of the yolk appears comparatively transparent. After several minutes the outer spot reaches the surface, and is less sharply marked, probably because of the increasing transpar- ency in the surrounding substance. The deeper spot is now very near the centre of the yolk, and only faintly indicated. After a short time the outer spot is flattened against the surface, and gradually acquires a greater superficial extent. There is now a slow accumulation of per- fectly clear protoplasm at this side of the yolk; it is thickest where the light spot first touched the surface, and thins away gradually on all sides. This is all accomplished in about an hour after extrusion, though liable to some variation, the changes being more rapid in proportion to the elevation of temperature. MUSEUM OF COMPARATIVE ZOOLOGY. 179 Up to this time the egg has remained without perceptible change of outline. With continued increase in the extent of the cap of clear protoplasm, which in section appears crescent-shaped, there is a slight elongation of one axis of the yolk, which gradually becomes more notice- able in the form of a low conical elevation at the side already indicated as that toward which the central spots tend. For the sake of precision I will call this the animal pole of the yolk, the opposite, the vegetative pole. Thus far the changes, whether within or without, have been so slow as to be recognizable only after the lapse of some minutes; but now ‘there begins at the middle of this crescent-like thickening a more rapid movement. The centre of this clear portion of protoplasm rises promptly in the form of a low, rounded eminence, of limited extent, which first becomes somewhat conical, and then assumes a more rectangular out- line, in that its sides become nearly parallel. In this condition, it is really a low cylinder, with one end free and rounded, the other in con- tinuation with the vitellus. (Fig. 1.) Sometimes this elevation seems to remain almost entirely free from opaque substance ; at other times, gran- ules accumulate to such an extent as to make the central portion of the protuberance appear very dark in transmitted light, and correspondingly white when seen by reflected light. The outline of the protuberance is sometimes slightly irregular and angular, although usually it is quite full and rounded. Without cessation it continues to change, principally by the mutual approximation of the sides of the cylinder at its base. This approximation takes the form of a constriction which is at first (Fig. 2) a broad furrow extending all around the cylinder. This furrow grad- ually becomes narrower and deeper (Fig. 3), and the excrescence which is thus being cut off takes a distinctly rounded form. The granulations now often appear gathered into the distal portion of the protuberance. Finally, the constriction deepens until there is only a slender thread of protoplasm joining the smaller and the greater sphere. This often per- sists for some time (Fig. 15), but finally ruptures, and sets free a small spheroidal body, with perfectly sharp and delicate outline, which is the first ‘polar globule.” It is only five or ten minutes from its first ap- pearance till it has the form of a sphere attached by a slender thread. During the formation of this first polar globule other changes are taking place, to the consideration of which it is now necessary to return. The elongation of the yolk in the direction of the animal radius (as I Shall call that radius which terminates in the animal pole) is very soon followed by its flattening in the direction of the same line. It is the 180 BULLETIN OF THE animal rather than the vegetative pole which shows the greater degree of flattening. This modification of the general form of the yolk reaches its maximum as the constriction at the base of the polar cylinder begins to deepen. But it is not alone a flattening which is noticeable at this time: the whole contour of the yolk becomes conspicuously modified. Whereas, at the first appearance of the protuberance, it has already become slightly flattened, it still remains symmetrical as regards the polar axis. Very soon, however, it becomes irregular, and more or less angular in its outline, and often appears remarkably unsymmetrical. During these few minutes it is constantly undergoing a slow change of form, which seems to affect every part of the yolk, and to be accompanied by redis- tributions of the granular substance of the vitellus, so that now one and then another portion becomes more opaque. As the detachment of the polar globule comes nearer to realization, these changes become less no- ticeable,* and finally, when the act is completed, the yolk has resumed its spherical form, and shows the same clear, even outline which had previously characterized it for so long a time. At the close of this act, a single, poorly defined clear spot is seen near the surface at the animal pole. The region of this pole still retains to a considerable extent its transparency, and a thin surface portion of clear protoplasm envelops the yolk on all sides. It is thickest at the animal pole, and thinnest at the vegetative. The portion immediately underlying the polar globule sometimes presents a peculiar striate aspect, which I have been unable fully to explain by other methods of study. The appearance is that of fine parallel striations, sometimes having the same direction as the animal axis (Fig. 49), sometimes oblique to it, or, on the other hand (Fig. 27), of two systems of parallel lines crossing each other at a con- siderable angle. These systems of striations seemed to be changing in position, yet without any recognizable regularity. They are probably astral rays or fibres of a nuclear spindle. (See below.) Gradually the vitelline granulations encroach on this peripheral clear layer, and it almost or entirely disappears. Returning now to a consideration of the smaller sphere, it is found that the first polar globules differ considerably in size (25 p to 40 yw), in different eggs, even though the yolks be of uniform diameter. When entirely detached, the polar globule is quite spherical, and remains for a * In another species of Limax I have seen, since the above was written, very prom- inent pseudopodal elevations of the yolk at the animal pole toward the close of the formation of the second polar globule (Fig. 95). Compare the explanation of the figure, ae MUSEUM OF COMPARATIVE ZOOLOGY. 181 short time tangent to the vitellus; but soon there appears between the two a perceptible interspace, which continues to increase for some minutes. The polar globule occasionally becomes removed a distance equal to its own diameter; more frequently, it is somewhat nearer the vitellus when this separation ceases. It often remains for some time at a distance from the vitellus, and then the interval gradually diminishes again. At first I was inclined to think this might be due to a slow change in the form of the vitellus, and that the motion of the polar globule was consequently more apparent than real; but the more I have watched it, the less have I been able to satisfy myself that such is really the case. About an hour after the appearance of the first polar globule, — dur- ing which the external form of the yolk has remained without noticeable change, the crescent-shaped accumulation of clear protoplasm has disap- peared, and the clear spot has become obscured, and again more distinct, —there begins again the accumulation of clear protoplasm at the ani- mal pole, which, as before, varies much in its extent in different eggs. (Figs. 5, 10°) Two or three times I have noticed just at this epoch a very peculiar behavior on the part of the first polar globule (Figs.11-13). It seemed suddenly to give way on the side directed toward the vitellus ; and its substance, which became as suddenly changed from almost complete transparency to a granular and opaque condition, was rapidly projected toward the animal pole of the yolk, with which it seemed to come in contact. This certainly does not always occur, nor can I offer any sat- isfactory explanation of its occasionally happening at this particular instant, i. e. just before the first appearance of the second polar globule. I have thought it might be due to the possibility that a change in the form of the yolk causes the rupture of an unobserved delicate connecting filament of protoplasm. But that does not seem very probable, inasmuch as the distance between the vitellus and the globule is such as to allow the discovery of such a thread of connection, if one really exist. Occasionally there is to be seen in the yolk at this time a second clear spot, which lies much nearer its centre than the one which has now come to the surface and has become partially lost in the crescent of clear protoplasm. Usually one sees nothing of this deeper spot, owing to the abundance and opacity of the vitelline granules. The changes which accompany the production of the second polar globule are so nearly identical with those which mark the appearance of the first, that attention need be called to only a few points in which they seem to differ. 182 BULLETIN OF THE I have noticed that very often the constriction about the base of the second polar cylinder advanced much more rapidly from one side than from the other, so that the axis of the cylinder, or becoming globule, regularly assumed a direction quite oblique to that of the polar axis of the yolk, and that (Fig. 19) consequently the point of final attachment was uniformly at some distance from the animal pole. The second globule is very often somewhat smaller than the first, hay- ing three quarters or only two thirds the diameter of the latter. When first detached the second seems to push before it the first, but at length they assume positions alongside each other in contact with the vitellus. I have never observed the formation of more than two polar globules, and never, when traced under normal conditions, aless number. Neither have I seen anything which could be compared to a division of either of the already formed polar globules, nor yet, with the exception of a sin- gle somewhat doubtful case, any instance in which as many as three globules existed near a single vitellus. I have noticed no other constant differences in the polar globules. The interval between them and the vitellus increases after the detach- ment of the second globule, but subsequently both come to lie much closer to the yolk, almost always in immediate contact with it. Both often retain a spherical form for a considerable time, during several successive segmentations at least. In other cases, one or both exhibit an irregular and wrinkled appearance, due most likely, in all cases, to such a collapse and partial loss of substance as have in several instances been directly observed. I believe that there is no regularity about this, and that one globule is quite as likely to present this appearance as the other, if only one is thus affected. In this collapsed condition they continue to exist even in the most advanced stages. As is well known, they take no part in the formation of the tissues of the em- bryo. We will now return to a consideration of the vitellus. Much as in the case of the first polar globule, the changes in the form of the yolk which accompany the production of the second are followed by an externally quiescent state, in which the vitellus, having once more assumed the spherical form, seems to be resting from its labors. The crescent-like shell of clear protoplasm at the animal pole again suf fers the vitelline granules to encroach upon its acquired territory, so that the observer sees only a very neatly outlined sphere. It appears whitish, or slightly yellowish, in reflected light, and more or less opaque when viewed with transmitted light; it hangs suspended in the albu- MUSEUM OF COMPARATIVE ZOOLOGY. 183 men like a planet, and at its side the two polar globules, of the same exquisite outline, are poised like a pair of satellites. A careful exami- nation, even with reflected light, shows that the halves of the sphere are not quite alike. Notwithstanding the disappearance of the crescent as a distinct feature, the animal half still appears more glassy and not so white as the vegetative hemisphere, yet the one passes into the other without any abrupt transition. In transmitted light the distinction is even more apparent. Near this more translucent animal pole one may sometimes see a faint circular spot (Fig. 6) of still greater clearness, fading away gradually on all sides, but more often only a general trans- lucency of this half of the yolk is noticeable. Even this gradually vanishes, and there follows a period of still greater obscurity. The gran- ulations are grouped in ill-defined shadowy masses, which one feels like comparing to clouds, and again are re-grouped and re-distributed, ap- parently without definite order or effect. Sometimes, however, these changes have been observed to have considerable regularity. The most common appearance, though this has been seen only a few times, is that of a nearly equatorial zone (Figs. 21, 33, 36, 51) of protoplasm, from which the vitelline granules are almost wholly eliminated. The position of this zone varies somewhat in different eggs, and in the same egg has been observed gradually to alter in form and extent. Soon after its appearance, it is seen as a band of narrow surface exposure, but of great depth, so that in optical section (Fig. 33) it extends to near the centre of the vitellus, becoming thinner the nearer it approaches this point. The outline thus presented in a section is that of two narrow wedges with their bases lying in the surface of the yolk near its equator, and their apices directed toward, and almost reaching, each other. In the course of twenty or thirty minutes the zone has become broader (Fig. 36), and a sectional view shows that the deeper edge, corresponding to the apex of the wedge, has become much rounded, so that the zone is now limited to the more superficial portion of the yolk. After twenty minutes more have elapsed, it has become still further restricted in its centripetal ex- tension (Fig. 34), and is rapidly becoming indistinct on account of the encroachment of yolk granules. But these changes, as well as the less regular fleecy appearances which are more frequently observable, are ac- companied by no corresponding alterations in the contour of the vitellus as a whole: the latter stills retains its simplicity of form. Such changes as have just been traced are not the only ones going on within the yolk at this time, although it is only in favorable cases that one has a view of other possibly more important phenomena. The 184 BULLETIN OF THE region of the animal pole, never losing wholly its unlikeness to the rest of the yolk, after a time shows a faint light spot of more or less cir- cular form. At first this spot is always poorly defined, and in many cases remains thus as long as it continues to be visible. In other cases, especially when it is nearer the animal pole, one may at length discover a clear-cut delicate outline, which always remains concave toward the centre of the spot. The latter is usually circular, but sometimes it is oval, and sometimes it has the form of an irregular body with rounded angles. This nuclear body continues gradually to increase in size, and at the same time to undergo slow changes of form, which, however, have never been seen to exceed the limits above indicated. When it has reached the size of the smaller polar globule, or somewhat earlier, a second like clear spot is seen lying deeper in the vitellus, and conse- quently less clearly defined (Figs. 21, 36). These bodies at first appear homogeneous, and less refractive than the surrounding protoplasm. Very soon, however, a few (1—3) small highly refractive corpuscles (nu- cleoli) may be seen in them at some distance from each other. They change their relative positions only slightly, as though passively shifted by the changes in the form of the nuclear body. The corpuscles in- crease in number, but I have not observed a division in any of them. The increase in the size of the nuclear bodies is quite gradual; they may attain, however, (Fig. 65,) a very considerable diameter (35 y). They are respectively, the first, the so-called egg-nucleus, or female pro- nucleus ; the second, the male pronucleus. The formation and growth of the female pronucleus, which occupies from one to two hours, according to temperature, constitutes the last series of changes which belong to this head, — the phenomena of matu- ration, — and we may now direct our attention to the results obtained in studying this phase of egg development by other means. For the purpose of pursuing the phenomena transpiring within the yolk, — which for the most part can only be traced with difficulty, or not at all, in the living specimen,-—one may have recourse to treatment with various reagents. Acetic acid has furnished the means to this end in the greater part of my studies. The condition presented by the least advanced eggs which I have been fortunate enough to secure was such as to contribute almost noth- ing to the solution of the question, What is the exact relation between the germinative vesicle and the first, or maturation, spindle? The eggs of Limax are not favorable objects for the study of this important ques- tion, — which has of late been agitated with such a fair prospect of a MUSEUM OF COMPARATIVE ZOOLOGY. 185 satisfactory solution, —and for this reason: the changes accompanying the metamorphosis are certainly initiated, and probably almost always wellnigh concluded before the egg is laid. At any rate, 1am sure that certain of the eggs (Fig. 39) I have treated were taken immediately after deposition. 'They were immersed in a weak preparation of acetic acid ; and yet, as before remarked, they were so far advanced as to afford little or no evidence toward the solu- tion of this question. The yolk thus early subjected for several hours to the action of weak acetic acid within the normal egg envelopes, and then carefully freed from all enveloping substances and treated with Beale’s carmine, shows already two well-marked stars, whose peripheries are in -contact, the whole forming the figure recently named by Whit- man “archiamphiaster,” to distinguish it from similar figures, known as “‘amphiasters,” which arise later in the history of the egg. This archiamphiaster occupies the middle of the vitelline sphere. The two stellate figures composing it are of equal size. Each is formed by straight radiating filaments of protoplasm, which converge from all directions toward an imaginary centre, which they never appear to reach. These filaments are differentiated portions of an otherwise nearly ho- mogeneous protoplasmic mass, which has a spherical form, and tolerably definite, though by no means sharply marked outline. The extent of these two spherés is marked by the encroachment of the coarse deuto- plasmic granulations held in suspension by'the remaining protoplasm of the yolk, and their outlines are consequently more or less definite, as this encroachment is more or less abrupt. In no case is this so sudden as totally to obscure the continuation of a few of the radiating lines, for a short distance, into the more granular portion of the protoplasm. As at their peripheral ends, so, too, at their central extremities, these - filaments do not all terminate ata uniform distance from the mathemat- ical centre of their respective spheres. Consequently there is a small space immediately surrounding this imaginary point of convergence, which, although in general of a spheroidal form, may be much less regu- lar in outline than a circle, and is not very definitely circumscribed. In optical section it appears as a more or less circular homogeneous “ area.” It is only a little more deeply stained in carmine than is the surrounding protoplasm. While most of the filaments composing the stars, or suns, are of the same thickness, there seem to be a few that are rather more prominent. These latter occur at intervals of 30° to 60° throughout the suns. It is 186 BULLETIN OF THE not always the stouter lines, however, which are traceable farthest from the centre. The diameter of each of these sun-like or astral spheres is about one third that of the whole vitellus, and their centres are so situated as to divide the diameter of the yolk into three nearly equal portions, so that | the two astral spheres appear at first sight to be simply tangent to each other. A more careful examination shows that this region of contact presents important, though not prominent, modifications of structure. All the fibres for some distance around the point of tangency are contin- uous from one sphere to the other. The stout fibres are here compara- tively more numerous than in the other portions of the figure, and all are more or less curved; those farthest from the central point of con- tact are most curved. This bipolar mass constitutes a spindle-shaped body, having its apices at the centres of the two spheres. It is the “ Richtungsspindel ” of German writers. I shall call it the “ maturation spindle.” The fibres which help to form it differ so little from the radial filaments of the suns that it is difficult at first to distinguish between the two. There is, however, still a third peculiarity which helps to empha- size this difference. The fibres of the spindle are slightly thickened midway between the two poles. These thickenings form the nuclear plate (Kernplatte) of Strasburger. From the results of recent obser- vations made on more favorable objects by numerous European ob- servers, there is every reason to believe that this spindle-shaped body is the result of the direct metamorphosis of the germinative vesicle, or at least of a part of it. A careful examination, however, of all the early stages I have seen, has failed to show satisfactorily anything of the germinative vesicle, which a somewhat earlier stage would probably have disclosed.* I cannot avoid repeating the fact that, at this stage, the spindle fibres are very inconspicuously differentiated from the radial fila- ments. Except for much more satisfactory views at a later stage, I confess I should have been somewhat sceptical about the existence of such a structure distinct from the stellate figures. It will be noticed that already the vitellus has no longer an homaxial form, but is monaxial. The differentiated axis corresponds to that of the maturation spindle; and its two poles are, so far as I have been able to discover, absolutely alike (haplopolar condition). This state * In one case (Fig. 39) I saw near the plane of the nuclear plate outside the spindle a few irregularly shaped bodies considerably larger than the granulations surrounding them, which may possibly have been remnants of the germinative dot, or of the mem- brane of the germinative vesicle. If not the remains of nuclear substance, I know of nothing with which they might be compared. MUSEUM OF COMPARATIVE ZOOLOGY. 187 is of short duration. Ata subsequent stage it will be seen that this monaxial haplopolar form is followed by a monaxial diplopolar. Po- tentially, I believe, this diplopolar condition already exists. In the present state of our ignorance as to the nature and residence of the forces which control the phenomena connected with maturation, it is not possible to find direct evidence of such a state at this early stage. In the eggs of many other animals, the diplopolar condition is manifest much earlier.* The protoplasm of the yolk not embraced by the spindle and amphi- aster is closely crowded with highly refractive deutoplasmic granules, which do not exhibit any system of arrangement, save that they are uni- formly distributed. These granules are irregular in form after the action of acid, and they vary considerably in size. In any optical sec- tion, the peripheral portions of the yolk appear more translucent than the central portions, not necessarily because of less abundance or less density of the deutoplasmic elements, but simply from the diminished amount of yolk substance which the light has to traverse to reach the observer's eye. It would not be true, however, to say that the granulations extend quite up to the surface of the egg. There is a very thin, almost imperceptible layer of substance, free from deutoplasmic elements, which forms the outer envelope of the yolk. This is in no way to be con- sidered as a vitelline membrane ; however sharp the external boundary may be, the internal portion merges so gradually into the yolk substance as to afford not the slightest ground for assuming that it is a distinct membrane. It is hardly necessary to add, that there is no evidence of a double contour, and that all attempts to separate as a distinct structure _ this outer condensed portion of the yolk are quite futile. As will be seen from Fig. 39, the uniformity in the distribution of the yolk granules is interrupted at irregular intervals (a). Spaces im- mediately contiguous to the surface of the yolk appear to be quite destitute of granules, and the corresponding portions of the surface are often raised into transparent, boss-like protuberances. These spaces — a dozen or more in number — are irregularly distributed over the whole yolk. They at once become conspicuous when the egg is placed in * Iam unable to say whether the axis of the yolk corresponding with the axis of the maturation spindle is identical with that which becomes differentiated at the formation of the polar globules. If so, then the migration of the spindle is only a motion of translation along this axis ; but, on the other hand, if the spindle at any time assumes a position oblique to the radius which passes through its centre, it is probable that the axes are not the same. 188 BULLETIN OF THE Beale’s carmine. One may perhaps seek an explanation of this appear- ance in a want of uniformity in the imbibition which takes place as soon as the egg comes in contact with the ammoniacal carmine. This view is, moreover, strengthened by the appearance of the exposed, thickened layer of protoplasm which envelops the yolk. For in the region of these spots the outline becomes less dark and conspicuous, as though a softening of the envelope had here allowed a portion of the proto- plasm to become less dense, and therefore feebly refractive. On the other hand, a subsequent falling in of the surface at these points — such as might naturally be expected, from the above explanation, to follow when the object is placed in a more dense fluid, like glycerine — has not been observed ; on the contrary, these areas continue to be raised conspicuously above the common level of the surface of the yolk. The protuberances have the appearance of quite naked, protruding por- tions of clear protoplasm. Whether they are anything more than the result of artificial ruptures of the cortical substance of the vitellus it is difficult to say. That they may be due to the presence of spermatozoa, which have already penetrated the yolk, is perhaps not impossible ; but it appears to me unlikely from the irregularity in the size and configu- ration of the spaces, as well as from the entire absence of any regular arrangement (stellate) of the granules in the surrounding protoplasm. I have not discovered any specially modified central portion, nor any difference between the spots and the immediately surrounding proto- plasm in the facility with which staining is effected. I have not ob- served anything of this kind in eggs of more advanced stages. What has been said of this earliest stage is based, unfortunately, on a limited number of specimens ; and, although my notes are unequivocal in declaring the eggs in question to be fresh-laid, I have not been able to entirely free my mind from the suspicion that, after all, they are much older than I have given them credit for being. The very considerable size of the amphiaster is perhaps in itself enough to suggest the possibility » that they were nearly ready to effect the first cleavage, and that the aster is, consequently, the first cleavage amphiaster. The considerations, however, which incline me to the belief indicated above are, in addition to the notes proving the freshness of the eggs, the following : — 1. The almost exactly central position of the amphiaster. This, it is true, would hardly be a safe criterion to distinguish this amphiaster from that of a second archiamphiaster, (as we shall presently see,) but is, it seems to me, very strong evidence that we have not to do in this case MUSEUM OF COMPARATIVE ZOOLOGY. 189 with the amphiaster of the first cleavage nucleus; for the latter has a conspicuously eccentric position, — it lies nearer the animal than the vegetative pole. 2. The somewhat sharper limitations of the protoplasmic spheres (stellate figures) than prevails at the time of the first and subsequent segmentations. And, finally, — 3: The appearance presented by the thickened envelope of the vitellus, which seems to possess less consistency than during the later stages, and even at intervals to be altogether interrupted. This I take to be an indication of want of age. I have not been fortunate enough to secure eggs in which the matura- tion spindle exhibits a position oblique to the radius passing through its centre, if I except a single specimen (Fig. 53), which I am inclined to consider as a case presenting the second rather than the first archi- amphiaster.* (See pp. 206, 207.) The next stage which has been observed (Fig. 45) is one in which the first maturation spindle has a radial position, one of the stars being at or near the centre, and the other reaching with its rays very near to the surface of the vitellus. The peripheral extremity of the radius in which this first spindle lies marks an important place in the topography of the ege. From this time on it forms a cardinal point, to which one may refer all changes of form. It is the point which we have already desig- * The reasons for considering Fig. 53 as that of the second archiamphiaster, instead of the first, are : — 1. The egg is one of a series of seven taken immediately after their deposition by the slug. Four of these were at once subjected to the acid, and all show the first polar globule in an advanced state of formation. This was submitted to acid nearly thirty minutes later, and consequently would have had time to accomplish the elim- ination of the first polar globule, and effect the metamorphosis which its supposed condition implies, provided it was equally advanced with the others. 2. The appearance of the yolk at the surface near the more superficial of the two asters. In the shallow depression of its surface and the ragged edges which it presents, the yolk so completely resembles the appearance of the vitellus after the production of a polar globule, that I am inclined to believe that the globule has been detached and escaped notice. _ 38. The smaller size of the peripheral aster. It is probable that the internal star of the second archiamphiaster is the more direct (if not the exclusive) genetic suc- cessor of the single star remaining at the closing phases of the detachment of the first polar globule, and therefore may be expected to be somewhat more conspicuous than its more recently formed companion. This last argument would have no weight if the second amphiaster arises, like the first, from the metamorphosis of a typical nucleus, since then both stars would be of equal age. (Comp. p. 206.) 190 BULLETIN OF THE nated as the anzmal pole. It is often spoken of as the formative pole, in distinction from the opposite and often less active nutritive pole. In this condition, then, the egg manifests a diplopolar state, which may — doubtless must — have had a potential existence before ; a state which is now most emphatically expressed by its internal structure, and which seems never to forsake it altogether. Whether, however, this monaxial state be identical with that which one observes in the earlier condition of the egg (Fig. 39) must be left undetermined for the present. | In this stage the maturation figure (i.e. the whole internal figure) presents itself as a compound structure, composed of the spindle and two nearly spherical masses of protoplasm, having the ends of the spindle as centres, and traversed by fibres radiating from them, — in short, the two asters of the so-called archiamphiaster. The length of the spindle is a little more than one third the diameter of the vitellus, and its greatest thickness is somewhat less than half its length. Its outline, when viewed en face, is evenly curved, tapering from its greatest thickness at the equator toward either pole, where it is lost in the rays near the centre of the aster. The spindle embraces a large number of fibres, — probably not less than thirty or forty, — continuous from pole to pole. These fibres are considerably more conspicuous than the radiating lines of the asters. The intervening substance of the spindle appears structureless, and much less refractive than the sub- stance of the fibres. Some of the latter exhibit, in the equatorial plane of the spindle, thickenings of considerable size. It does not seem that all the fibres present such thickenings ; nor, on the other hand, am I quite certain but that some of these apparent thickenings are really unconnected with any fibres, —at least their irregular distribution has suggested the possibility of their being de- tached, without having afforded as yet a sufliciently satisfactory demon- stration of the existence of such independent granules. A view along the axis of the spindle (Fig. 46), while it affords pretty satisfactory evidence as to the relative position of the thickenings in the equatorial — plane, does not prove sufficient to settle the question, for the reason that the fibres are so minute as to be almost entirely obscured by the overlying star. In the view thus had, one finds the number of thick- enings to be about twenty, and that they are not distributed with any very clearly defined order. In a later stage, however, we shall find that the number is considerably greater, and that they are more conspicu- ously subject to a definite plan of arrangement. oe MUSEUM OF COMPARATIVE ZOOLOGY. 191 The two stars, or, more exactly, spheres, of the first maturation figure already present a difference which is not diminished as the de- velopment of the egg advances. Not alone that there is a noticeable difference in the magnitude of the two stars, constantly somewhat to the disadvantage of the peripheral one, but, further, there is a sharpness to the limitation of the outer star which is missed in the outline of the central figure. Nor is this attributable solely to the obscuration pro- duced by the rays of light from the deeper star having to traverse a greater mass of granular vitelline substance than do those from the more superficial figure. No doubt that fact enhances the difference, but the primary cause seems to lie in the more complete exclusion of the granu- lar elements of the vitellus from the superficial than from the deeper sphere. In another point, too, these two stars may differ: the rays of the outer star, instead of presenting that rectilinear appearance which characterizes those of the deeper star, appear uniformly curved in a like direction (Fig. 47) when the star is viewed from the animal pole. This spiral arrangement of the radiating fibres of one or the other of the am- phiastral stars is a phenomenon of not uncommon occurrence, and will demand a more extended consideration a little further on. It is a less constant feature of the outer star than the peculiarities previously described. Aside from these differences, there seems to be no noticeable distinction between the two asters or their relations to the portions of the spindle so closely connected with each. There is, however, one feature which very soon makes its appearance, or may perhaps be already detected in a faint degree, — I mean a modification of the form of the superficial sphere, which is accomplished at the expense of the diameter which coincides with the polar diameter of the yolk. To be more exact, however, this flattening in the direction of the animal radius is most conspicuous, if not exclusively apparent, on the outer hemisphere of the superficial aster. It is a modification which increases with the motion of translation which the whole internal figure is destined to undergo along this animal radius; it is perhaps only one of the physical effects resulting from the motion. When this maturation figure is spoken of as though it were something by itself, it is not to be understood that it is a sharply defined object with definite boundaries separating it from the remaining portions of the yolk, but, on the contrary, it should be distinctly stated that at this stage the transition from the maturation figure, on the one hand, to the en- veloping portions of the vitellus, on the other, is quite gradual. The latter is characterized by the deutoplasmic elements, which are 192 BULLETIN OF THE evenly distributed through its mass, save where they come within the reach of the influence which determines the differentiation of the sub- stance of the maturation figure into less refractive and more refrac- tive fibrous portions having a definite arrangement. Here these coarse deutoplasmic elements are made to assume a corresponding radial rela- tion. ‘They decrease in abundance toward the centres of the stellate figures. The figure of the whole vitellus is that of a sphere, which may already be slightly flattened in the direction of the only differentiated axis.* The portions which are most deeply stained in carmine are, first, the equatorial thickenings of the spindle, and after them the central portions of the two asters. The gradual increase from periphery to centre in the density of each aster makes it more and more difficult, as one approaches the centre of the star, to distinguish the compact proto- plasmic rays from the protoplasm in which they are imbedded. For this reason the “area” is not always at this time a region definitely circumscribed by the central terminations of the radial fibres. In the stage just reviewed we have seen the first archiamphiaster fully formed, and already advanced to a position such that a continua- tion in its motion of translation will necessarily make itself at once apparent in the general outline of the yolk. Such a modification is, in fact, the thing which, in the next stage (Figs. 43, 48), most forcibly attracts attention, — not, however, in the manner one might have antici- pated. ‘The whole vitellus becomes conspicuously flattened in the direc- tion of its polar diameter, and at the same time presents at the animal pole, as a sort of compensating change, a slight elevation. The latter becomes prominent in proportion as the vitellus, as a whole, undergoes further depression at this pole of the egg. It is as though the vitellus at the animal pole were to sink gradually away, leaving the peripheral end of the archiamphiaster protruding beyond the general outline. The latter, as seen from either pole of the main axis, remains that of a circle, or at least presents only very slight and inconstant deviations from that form ; but the outline, as seen in profile, becomes altered, not simply, as it would seem, by the protrusion of the maturation figure, but by a concomitant flattening of the adjacent portions of the vitellus. The relation of these two acts to each other and to their cause will be con- sidered hereafter. The resulting outline is like that produced by the insertion of the arc of a smaller circle into that of a greater one. The * For the peculiar appearance of the outline at the animal pole of the vitellus in Fig. 45, see the explanation of the figures. MUSEUM OF COMPARATIVE ZOOLOGY. 193 inserted are corresponds to a circle having approximately the diameter of the outer stellate sphere. The resistance offered by the yolk en- velope is, however, so considerable as to cause a decided flattening of the external half of the peripheral stellar sphere. It also results from this resistance that the outer ends of the radiate filaments of the outer star are curved away from the polar axis, and finally bent backward, — much as the hairs of a soft brush would be when gently forced against the concave surface of a highly curved watch-crystal. The effect of this curvature in the filaments is at first quite deceptive ; for it unmistak- ably suggests to the observer that from the apex of the protuberance there is a funnel-shaped depression extending to near the centre of the radiate figure, — a depression in form something like that of the corolla of a morning-glory. This illusion is further heightened in specimens which have been stained, by the fact that this apparently invaginated portion is only slightly tinged in comparison with other portions of the stellate figure, or the yolk (Fig. 43). It is, however, very certain that no such depression actually exists, as one may be convinced by care- fully rotating the egg and focusing the instrument so that the centres of both stellate figures are seen distinctly at the same time. The axis of the spindle then lies in a plane parallel with that of the microscope stage, and its whole length is exactly in focus. If there were such a depression at the surface which lies in the continuation of the spindle axis, it should be observable in the outline of the yolk ; but, on the contrary, the very transparent portion of the peripheral star shows a sharply defined outline, convex externally, and continuous at each end with the outline of the rest of the yolk (Figs. 43, 48). When the egg has been subjected to the action of acetic acid, the very fulness of the outline at the animal pole, as contrasted with the more or less shrivelled and irregular outline of the rest of the vitellus, is to me an indication of the high state of mechanical tension to which this portion of the surface is subjected. At this time the superficial portion of the protuberance seems to be- come differentiated into a thin membrane with double contour, which is continuous at the margin of the elevation with the less conspicuously differentiated outer layer of the rest of the vitellus. This membrane is at first of uniform thickness over the whole surface of the protuberance. It is only in a subsequent stage that it assumes a different and peculiar appearance. As already indicated, the radiating fibres of the peripheral aster suf- fer a bending back, which changes their original direction more or less, VOL. VI. — No. 12. 13 : 194 BULLETIN OF THE according as they would naturally lie near to, or more remote from, the continuation of the spindle axis. The course of some of the fibres of even the deeper half of this star is thus affected. The result is a gradual diminution in the number of fibres in the outer half of the aster, and their greater concentration near the equator of the astral sphere. It is this increase in the number of the fibres near the equa- tor of the aster, together with their arched course, which causes the peculiar funnel-shaped phenomenon already described. Such sim- ple, and yet unique, modifications of the star are not the only ones to be found. While I believe the backward deflection of the fibres is an invariable, a mechanically necessary feature of this stage of the egg phenomena, I am not able to say as much of some other modi- fications ; in fact, Iam almost certain that the latter are to be found only occasionally. ‘They may not, perhaps, on that account, prove less interesting. I refer to the very peculiar appearance sometimes pre- sented by the outer aster, when one looks directly down upon the animal pole of the egg. Instead of seeing the fibres radiate in straight lines, as one might naturally expect and would find in the majority of cases, it will often be discovered that they are uniformly bent into a spiral, pre- senting thus a figure not unlike that of a turbine water-wheel (Fig. 56). The curvature in the cases I have seen (remembering that the observer is looking upon the animal pole) is such as would be produced by the peripheral ends of the fibres being moved in the direction in which the hands of a clock advance, while the centre remained fixed, or by an opposite rotating motion of the axis of the spindle when the peripheral ends were immovable. This spiral phenomenon has been observed even before the aster had “caused any elevation of the surface (Fig. 47), but not before it had reached the periphery of the yolk. No phenomena corresponding either to flattening, backward deflection, or spiral arrangement of the fibres, have been observed in the deeper star up to this stage. During the stage now under consideration the centre of the peripheral sphere becomes conspicuously modified. It is at length occupied by a circular, highly refractive homogeneous body, flattened in the direction of the axis of the spindle so that it appears oval in a profile view. This body, at times irregular in outline, appears to be surrounded by a clear zone of uniform thickness. The appearance may be due solely to reflection from the body itself. (Comp. Flemming, "78, p. 310.*) * The numbers immediately following an author’s name serve the double purpose of referring the reader to the list (p. 591) where the titles of papers are given, and of in- forming him at once of the approximate date of: the paper in question. MUSEUM OF COMPARATIVE ZOOLOGY. 195 The uniform thickness of the zone would favor this interpretation ; on the other hand, it is sometimes too broad readily to admit that expla- nation. This body is the centre of the peripheral radiation, and corresponds consequently to the centre of the deeper stellate figure. In the latter, however, I have not usually succeeded in finding any correspond- ing well-defined structure. As in the earlier stages, one sees only an irregular area, often homogeneous, but at times apparently made up of a small number of coalescing, not highly refractive globules. (Comp. Fig. 55.) In only one case (Fig. 48) have I seen anything like a sharply limited body in the centre of the deeper aster. In this case it was of about the same size as the peripheral body, and like it appeared slightly flattened in the direction of the spindle axis. Still, the outline was less sharp, and the flattening less conspicuous. The impossibility of fixing with accuracy the absolute, or even rela- tive, degree of advancement of different eggs at this period, deprives the observations in great measure of the value they might other- wise have. This would be especially perplexing were it not that one is at liberty, when the evidence is so uniform, as it fortunately is in this case, to use the observations of others, even though made on differ- ent animals. Not that there is no direct evidence of which to make ase, but simply that it is less complete than it would have been, had the eggs been more transparent. The spindle at this stage is not always prominent. In some cases (Fig. 43) it is with great difficulty that its fibres can be distinguished from the radiate filaments. At other times, when the superficial pro- tuberance and the central body of the aster are already differentiated, its limits are very well marked. Thickenings in its fibres are often not easily made out. Even where there is a prominent elevation of the yolk and a sharply marked body in the outer aster, the central zone of the spindle sometimes appears as hardly more than a continuation of the granular protoplasm which, in optical section, seems wedged in between the surfaces of the stellate spheres (Fig. 43). On the other hand, eggs in which the elevation is less pronounced (Fig. 48) may present a clearly marked median zone of thickenings, or even two closely approximated zones. Figs. 43, 48, (and others not reproduced on the plates,) evidently exhibit slightly different stages, although the eggs were deposited in one bunch, cer- tainly not more than a few seconds apart, and were subjected to the same treatment. The prominence of the stellar elevation, which might 196 BULLETIN OF THE at first appear to be a fair index to the advancement of the individual eggs, seems to be of secondary importance ; for in this series the one (Fig. 48) presenting the least elevation is the one which, to conclude from the appearance of a subsequent stage, as well as from analogy with observations on the eggs of other animals, is in reality the most advanced. The evidence is found in the fact that there are two zones of thickenings here, while in the others only one zone is discernible. It has been clearly shown, by direct observation of living cells of both animals and plants, that this double zone arises by the splitting into halves of the single median zone ; and that such is really the case here cannot be doubted, as we shall see when we come to the investigation of the next stage. Moreover, a careful examination of the figures shows that the centre of the outer star is nearer the surface (whither it was certainly tending) in the eggs which, for reasons just given, we must conclude are the more advanced. The spindle, as in the preceding stage, is usually very stout, its thick- ness at the equator being nearly half its length, which still remains about one third the diameter of the vitellus. The arrangement of the granulations in the vitellus differs but little from that which prevailed in the last stage. There still exists a uniform distribution of these elements save where the archiamphiaster has caused their more or less extensive disappearance. Corresponding to the changed position of the archiamphiaster, the area of distribution is somewhat modified ; but otherwise I can discover no alteration in eggs subjected to hardening processes. The further transfer of the archiamphiaster toward the surface of the vitellus is accompanied with continued changes, which affect its shape more than the general form of the vitellus. Instead of pushing be- fore it the thin covering formed at the animal pole, and emerging from the surface as a complete spherical aster, the exposed half of the outer star suffers a further and marked change of form, as well as re- duction of size (Fig. 50). The centre of this stellate figure now lies close to the surface of the vitellus, a thing which could only occur by a displacement in the more exposed radiate fibres. What the nature of that displacement is, can be inferred from what was seen in the last. stage, where a mechanical deflection was so apparent. From the position of the centre of the outer star, it follows that the latter is now much less than a complete sphere; it is even much less than a hemisphere. The radial extent of the portion which re- mains is, however, about the same as before, that is to say, the radiating MUSEUM OF COMPARATIVE ZOOLOGY. 197 fibres are of nearly the same length. Consequently the inner limita- tion of this outer aster—the surface which abuts upon the granular vitellus — is, as before, of nearly circular outline; the free or exposed portion, on the other hand, has not quite the form of the are of a circle, for the curvature is sharpest at a point directly over the centre of radia- tion, The course of the adjacent rays is nearly parallel with this outline. The whole figure of the outer star is thus changed from a sphere to a form more resembling a biconvex lens, va its more highly curved surface directed outward. The compact body which in the earlier stages existed at the centre of radiation still persists, although its form is further modified by a con- tinued flattening. It is in the profile view that this body is most con- spicuous. It corresponds, I believe, with that which Robin (’75, p. 34) calls in Nephelis “‘un espace clair circulaire, superficiel,” but which has been better seen and more clearly depicted by Whitman (’78%, p. 18, and Figs. 62, 63, C. P.), in the case of Clepsine. I shall have occa- sion to recur to this subsequently. The modifications which the external aster has undergone, caused in part at least by its relation to the outer envelope of the vitellus, do not find their counterpart in a like modification of the deeper aster. A certain amount of change may also be observed here. This aster has also approached the animal pole; it has moved to a position at some distance from the centre of the vitellus; there is also a slight change in the extent of the radiate influence of which it is the expres- sion, for the rays which reach out into the vegetative hemisphere are somewhat longer than those belonging to the opposite half of the yolk. Its peripheral limitation continues to be less sharply marked than that of the outer star. The inner ends of the rays, on the other hand, terminate at a nearly uniform distance from the centre of radiation. The spindle itself still retains the robust proportions characteristic of the earlier stages. Its length has not suffered appreciable change, and its outline is less modified at the equator than in the earlier stages, when the bending at this place often appeared quite abrupt. The inter- stellate fibres are more distinct than formerly, and the centres of the stars continue to be the points of convergence for the two extrem- ities of the spindle fibres. The thickenings of the latter are more or less widely separated, and appear as two distinct and conspicuous zones at equal distances from the equator. When seen lengthwise of the spindle, the numerous (40 to 50) thickenings appear arranged — more distinctly than in the previous stage—in the form of a ring, 198 BULLETIN OF THE neither border of which is sharply marked. Between the two zones of thickenings are stretched delicate nearly parallel threads, which I shall designate as ¢nterzonal filaments. The granular elements of the yolk are distributed with the same uniformity as before, and are only so far modified in their arrange- ment as might have been anticipated from the changes in form, posi- tion, and extent of the archiamphiaster. The vitellus has again as- sumed more nearly the circular outline, aside from the protuberance caused by the archiamphiaster. That portion of the profile where this conical protuberance joins the sphere presents a very slight reverse curvature. In hardened eggs the contour of the low cone is constantly distinguishable from that of the remaining vitellus by a fulness and evenness which are quite as noticeable as in the preceding stages. This is the more conspicuous in some specimens from a thickening in the envelope of the vitellus at this pole. In extreme cases (Fig. 50) the thickness of this structure (vm?) may reach 3.5 at the pole itself, but it thins out rapidly, so that where the base of the conical elevation joins the vitelline sphere it is quite indistinguishable. It is sharply marked from the underlying stellate figure, and presents in glycerine a clear, even, though not prominent, external outline. Its substance is finely punctate, a thing which causes me to question the interpretation (vitelline membrane) which I was at first inclined to give this structure. In some cases, apparently in this stage of advancement, it is represented by only a thin homogeneous cortical layer such as is depicted in the preceding stage (Fig. 43).* The changes following upon the conditions last described lead directly to the production of a small, more or less spherical body at the animal * J am in no way prepared to insist upon the identity of these two structures. As regards the origin of that which is to be seen in Fig. 43, I have no hesitancy in re- ferring it to a cortical portion of the yolk itself. The structure exhibited in Fig. 50 presents peculiarities not easily harmonized with a like explanation of its origin. Foremost is the fact of its low refracting power; secondly, its finely granular struc- ture; and, finally, its very unequal thickness within narrow superficial limits. Whether it may not be a comparatively thin fluid exudation from the animal pole of the yolk coagulated by the acid, or whether it may not owe its origin to the albumen surrounding this region of the vitellus, are possibilities which I have not been able definitely to accept or reject. If in any way dependent on the albumen for its origin, it is difficult to understand what should induce it to take this very peculiar form, and why it has so sharp and even an exterior. I can recall nothing in the development of other animals with which it may possibly be compared, unless perhaps with the exudation from the eggs of Batrachia, described by Bambeke and O. Hertwig. MUSEUM OF COMPARATIVE ZOOLOGY. 199 pole, —the so-called polar globule. The steps in its formation have already been followed in the living egg, in so far, at least, as concerns the successive phases of its changing outline. The slight annular depression marking the limit of the external aster in the previous stage gradually deepens, and the transparent fibrous protoplasm of the outer star, together with a portion of the more granular protoplasm in its immediate vicinity, is pinched off by this deepening constriction. The internal alterations accompanying this process (Figs. 40-42) are in a measure only the continuation of those noticed in the last stage. The maturation figure has migrated farther from its central position. The external star has undergone a more thorough metamorphosis than the deeper one. ‘The spindle has suffered a constriction at its equator, but its length remains nearly unaltered. What is left of the radial structure of the outer star is discoverable within the polar globule. A few faint lines, lying mostly near its sur- face, are all that can now be seen; even these are not uniformly observ- able. When present, they are often so closely applied to the surface of the polar globule as to leave the observer for a time in doubt if he has not before him a series of striations or foldings in the envelope of the globule. The slightly serrated outline of that portion of the globule which in Fig. 41 faces the vitellus, seems at first to strengthen the lat- ter opinion ; but a careful inspection seldom fails to show that the mark- ings are not all parallel, — that different systems cross at a slight angle, which could hardly be expected of surface foldings. The greater part of the contents of the polar globule show not the least.trace of such a structure, but are simply either quite transparent and homogeneous, or show a very fine punctate appearance, in which a few larger granules are occasionally found. The structure of the central portion will receive attention a little further on. The body which formed the centre of radiation is usually no longer distinguishable, its substance possibly hav- ing become disseminated in the globule. Occasionally, however, (comp. Fig. 63,) one discovers, attached to the free pole of the globule and pro- jecting inward, a prominent thickening (aa’?) which I am inclined to consider as at least a portion of this refractive corpuscle which has by this time gained an intimate connection with the envelope of the globule. The deeper star, having moved further from the centre of the yolk, as already indicated, is now tangent to the inner surface of the vitelline Sphere. The amount of substance that is brought directly within the influence of this star is slightly increased, principally on the side opposite 200 BULLETIN OF THE the polar globule. It should be remarked, however, that the extent of this influence, as evinced in the radiate structure, is subject to consider- able variations in different eges at the same stage of development. While a homogeneous area at the centre of this star is marked off at times with great distinctness (Figs. 22, 25), in other cases the central portion is less prominent. It may continue to present the appearance previously noticed, as though originating from a few irregular and poorly defined masses of nearly homogeneous substance. One side of this cen- tral area is marked in a conspicuous manner, as will be seen presently, when the structure of the spindle is considered. The latter has now become very much modified, and, by the advance of the constriction, is made to assume successively different forms, until at length it is like two spindles placed end to end rather than a single structure. What we may call the outer spindle, i. e. the outer half of the original body, which now occupies the polar globule, is less spindle- shaped than the inner half. I have never been fortunate enough to see its fibres converge beyond the zone of thickenings, after the constriction has made its appearance at the base of the polar globule. A slight con- vergence of the interzonal filaments toward a point on the distal surface of the globule is, however, often observable (Figs. 22, 63). After fur- ther constriction the region of thickenings appears more expanded, as in Fig. 25. The internal half often preserves for some time a fusiform appear- ance, though the theoretical apex at the centre of the stellate figure has no visible connection with its fibres. It is only the trend of the latter which indicates this point as coincident with the centre of the star. The place of interruption in the fibres is dependent on the size of the central area. Already at the beginning of the constriction the two lateral zones (or nuclear plates) had migrated, the one to near the border of the deeper “area,” the other to a corresponding position relative to the refractive body of the outer star. During the constriction the thickenings of the former are found grouped together at the periphery of this “area,” in such a way as to form a circular disk rather than a ring such as was observed in the earlier stages. The outer of these migrating zones, on the other hand, has not diminished in circumference, but .has spread out, and still presents the annular rather than the disk- like arrangement. When seen from the animal pole the spindle thickenings in the polar globule (Fig. 42) consequently appear as an ill-defined ring. MUSEUM OF COMPARATIVE ZOOLOGY. 201 That portion of the interzonal filaments which falls within the polar globule is gradually drawn into the thickenings; at least the fila- ments as such disappear. That portion which remains within the vitellus, after suffering a diminution in thickness, probably disappears altogether; so that shortly after the separation of the first polar globule there is found in the vitellus only a single stellate figure near the ani- mal pole. In the polar globule, on the other hand, there is no radiate structure, — simply a group of prominent granules which are conspic- uous from the readiness with which they are stained in carmine. The globule often gives evidence of being limited by a special membrane, which must have come from the envelope which we have traced in its origin as a covering to the rising cone of the animal pole. As that envelope was often thick at the apex .and rapidly grew thinner toward the base of the cone, so we find that the correspond- ing structure is often much thickened at the distal extremity of the globule (Fig. 22),—the point corresponding to the apex of the cone. This thickened portion passes gradually into the envelope of the sides and proximal face, which seldom shows more than a single contour line. Before the complete detachment of the globule, there is formed (Fig. 63), in the pedicel which still establishes a connection with the yolk, at a point corresponding more or less closely with the equator of the spindle, another thickening, which may be the equivalent of the cell- plate (Zellplatte) of Strasburger. It is a disk of considerable thickness, which extends quite across the pedicel, and is highly refractive. Though not directly observed, it is reasonable to suppose that the final separa- tion is along this disk, most likely by its division into two plates. The events which immediately follow the formation of the first polar globule seem to me to have been less clearly treated by those who have engaged in the study of the phenomena than any other portion of these remarkable changes. Nor can I add much to their elucidation ; for it is only after carefully comparing the results of my summer’s work that I am inclined to believe that there remains just here something of a gap in the continuity of the best observations. It has been cus- tomary for the second archiamphiaster to receive only a hasty de- scription. Its origin has often been quite neglected. Because the result in the case of both maturation spindles is the production of a polar globule, the phenomena in the second case seem to have been considered of only secondary value in the search for what is new. At the beginning of this second stage careful attention is demanded to answer the ques- tion, How does the second archiamphiaster arise 2 202 BULLETIN OF THE Does the spindle completely disappear? Or does the vitelline half persist ? And if it remains, does its outer end become the centre of a new force, acting on the surrounding protoplasm to induce a new pe- ripheral star? Or, if it vanishes, does the single star develop an- tagonistic poles which move apart, each taking with it the half of the great star left in the vitellus ? So far as one can judge from the observations that have hitherto ap- peared, the most nearly complete second archiamphiaster yet seen is one having a spherical central aster joined by a spindle to a very incomplete peripheral aster, whose centre of radiation lies in the surface of the vitellus. The latter in its greatest extension is less than the half of a complete star. That there have been important omissions from the history of the second archiamphiaster will at once be inferred upon consulting Fig. 23. The first polar globule has already been formed, but still remains loosely attached to the vitellus, and further held in place by fragmentary portions of the surrounding albumen of the egg (a).: The second archiamphiaster is completely formed. Its axis coincides almost exactly with the polar axis of the yolk. It lies wholly within the vitellus, being nowhere tangent to its surface. The nearest point of approach to the surface is immediately under the polar globule. The composition of this second archaic figure is deserving of close attention. The two stellate figures which make up the most of its substance are joined by a spindle which is not very distinctly outlined. Perhaps the most noticeable feature of the whole figure is the un- likeness of the two stars; such a difference as we have already seen (Fig. 45) in the first archiamphiaster. The outline of the deeper sphere is by no means sharp, for prominent rays here and there extend into the coarsely granular protoplasm for some distance beyond the majority of the radiate fibres. In the case of the more superficial sphere, on the other hand, the rays terminate at such a uniform distance from its cen- tre that the outline is quite even, and almost circular, in whatever posi- tion it be viewed. Otherwise the two asters are much alike: the rays are straight in both, though more uniformly distinct in the outer than in the deeper sphere. The centre of each is composed of a poorly de- fined, not quite homogeneous refractive substance, as in corresponding stages of the first archiamphiaster. The fibres joining the centres and together constituting the spindle are, as usual, slightly curved, and they already present inconspicuous thickenings in the equatorial zone. The granulations of the vitellus, although for the most part evenly MUSEUM OF COMPARATIVE ZOOLOGY. 203 distributed, show about the animal pole irregularities of arrangement, which at first sight give one the impression that the outline of the outer stellate sphere is not even. This is most noticeable when the view is upon the animal pole, as in Fig. 24. However, the archiamphiaster, seen in profile, shows — whichever way the vitellus is rotated about the spin- dle axis — that this appearance is produced by aggregations of granules quite outside the stellate sphere, and that really the surface of the latter is not invaded by these granulations. Inasmuch as the stage just described has not been seen by other observers, it will not appeag superfluous to state briefly the evidence that it is the second archiamphiaster. The stages with which this might most easily be confounded are without doubt that of the formation of the jirst archiamphiaster, and that of the jirst cleavage amphiaster. 1. The egg in question was one of four of nearly the same degree of advancement (Figs. 25, 22, 23, 57). Three of these were subjected to acid at intervals of ten minutes, the first (Fig. 25) being immersed on the appearance of a conical protuberance ; the second (Fig. 22), though ten minutes later, seems to have been hardly more advanced than the first. This one (Fig. 23), the third, was observed to have a conical ele- vation ten minutes before its immersion, although the elevation may | possibly have first appeared a few minutes earlier. It must have been then at the /east ten minutes after its appearance, and most likely more, perhaps even fifteen or twenty minutes, when the conditions here preserved became fixed. This in itself would be enough to preclude the possibility of the first mistake, even if the first polar globule were no longer to be discovered in contact with the vitellus.. There can be no doubt, then, that the first polar globule had already been formed, and that consequently the figure in question could not be the first archi- -amphiaster. 2. The second possibility may not at first appear so easy of refuta- tion. The position of the axis of the spindle relative to the already formed polar globule, it is true, is little in harmony with the inter- pretation of the figure as the amphiaster of the first cleavage sphere, and is exactly what we might expect of a second maturation spindle. Nevertheless, it might be urged that possibly the polar globule is no longer located at that point of the vitelline surface where it originated, and that consequently the relation of the spindle axis to the globule is quite valueless in determining the nature of the spindle ; for in that case the polar globule here figured might be the second, and the stellate figures accordingly could only be interpreted as belonging to the first cleavage 2.04. BULLETIN OF THE amphiaster. Aside from the fact that the egg in a living condition was under observation at least some ten minutes immediately prior to its im- mersion, during which time one could hardly have failed to distinguish a fully formed first polar globule, had such actually existed, there are other and sufficient reasons for construing the observations differently. Not only that the comparatively large size of the polar globule points to its being the first, rather than the second, and that a slight prolonga- tion from one side (p) is evidence that it had not yet wholly severed its connection with the vitellus, but it is especially the evidence within the vitellus itself that makes the above interpretgtion inadmissible. This can be understood only by reference to what will appear more fully in speaking of the amphiaster of the first cleavage sphere; namely, that the two stars of the cleavage amphiaster lie in a plane which is perpendicuar to the animal radius at a point much nearer the animal than the vegetative pole, and that they are of almost identical appear- ance, though often deviating considerably from aspherical form. (Com- pare Fig. 82.) None of these conditions are fulfilled by the figure under considera- tion. There is no evidence that any one of the lines perpendicular to the axis of the spindle at its middle * terminates at the animal pole of the vitellus ; and even if such evidence existed, the plane, which is perpen- dicular to such line and also passes through both the asters, would not be perceptibly removed from the centre of the vitellus. Moreover, while the two stellar masses are almost spherical, — and therefore unlike that which we might expect in the amphiaster of the first cleavage sphere (compare Fig. 82),—they differ from each other in the sharpness of outline already noticed, and thereby again fail to conform to the re- quirements of the indicated interpretation. Other objections, drawn from a comparison of this figure with the amphiaster of the first cleav- age sphere, might be adduced in answer to the possibility of this ex- planation ; but enough has been said already to place beyond doubt its true nature; it is the amphiaster that immediately precedes the forma- tion of the second polar globule.f * It is at once apparent from the figure that no such perpendicular could be a radius af the vitellus, from the fact that one end of the spindle is much farther from its cen- tre than is the other. ' + The possibility that one of the stars might be due to fecundation — might be the so-called male aster — has not been overlooked. But the intimate union of the two stars by means of a spindle which has an equatorial zone of granulations would make this extremely improbable, even if the method in which the two pronuclei become joined were less accurately known than at present. See pp. 224-229. MUSEUM OF COMPARATIVE ZOOLOGY. 205 It is an important question, How does the second archiamphiaster arise, and what relation does it bear to the first archiamphiaster 4 Very few observers have given this question special attention, and those who have are not all positive in their opinions. According to most of the descriptions given, the vitelline “half-spindle,” which remains after the formation of the first polar globule, simply undergoes an elongation caused by the gradual recession of the single remaining aster from the surface; the internal zone of fibre thickenings disappears by the distribution of its substance to form the lengthening fibres of the new spindle; and there arises a second stellate figure whose rays converge toward a point of the surface where the peripheral end of the spindle remains. Such an origin could not be directly compared with the for- mation of the first archiamphiaster, or subsequent amphiasters : it must be at best a greatly abbreviated process, if at all comparable with the ordinary method of amphiastral formation. In all other cases both cen- tres of radiation arise as new differentiations in the protoplasm, and only make their appearance when the nuclear substance has assumed a defi- nitely circumscribed form ; in this case (according to the authors) only one of the centres of radiation has the least claim to be considered new, and the nuclear thickenings do not become fused into a definitely limited nucleus. The case (Fig. 23) to which I have called attention presents some evidence that the second archiamphiaster is not formed in so direct a manner as has been supposed. There is no absolutely incontroverti- ble reason for denying that this complete amphiaster may have been formed much in the manner above indicated for the incomplete one. It would only be necessary to assume an extensive migration from the surface on the part of the spindle and its asters, instead of a movement on the part of the deep aster alone. There are, however, some objec- tions to this view. The spindle has the appearance of being formed in the ordinary way, rather than that of having its fibres drawn out ; it is not so sharply defined as I should expect a spindle to be, if resulting from a drawing-out process ; it is much broader, and its peripheral fibres more abruptly bent, than would be the case in that event. The fact of its being totally enveloped in the yolk is in itself more easily reconcilable with its formation in a normal than in an abbreviated manner, since in the former case the centres of radiation arise at points within the vitel- lus, and thus is avoided the necessity of supposing that there is a cen- tripetal migration of the spindle. We have seen that at the completion of the first polar globule the 206 BULLETIN OF THE lateral zone of thickenings belonging to the vitellus had already reached the edge of the central “area.” The vitelline half-spindle has been seen gradually to fade, but its complete disappearance I cannot affirm from direct observation. It seems to me not entirely impossible that its filaments are absorbed by the zone of thickenings, and that the latter is actually converted, as in the normal method, into a nuclear structure, in the vicinity of which two new stars (the second archiamphiaster) make their appearance. Both of these (the existence of a veritable nucleus, and the formation of two new stars) are only assumptions. I have no direct evidence that such a nuclear structure intervenes between the two archiamphiasters, nor that the two asters are both formed about new centres. There are only very slight indirect signs of such a condition, — indications that only warrant the suggestion of a possibility. I will not on that account withhold the observations. There is some reason for believing that the view presented in Fig. 53 is that of the second archiamphiaster in process of a rotation which would eventually have brought its axis into coincidence with the animal radius of the vitellus.* If such be the case, it seems quite probable that this whole figure originated from a nuclear structure, in much the same man- ner as the first archiamphiaster is known to arise from the germinative vesicle, and that consequently this second spindle was not durectly de- . rived from the first spindle, and that possibly both of the stars are new productions. The reasons already indicated for thinking it is the sec- ond, are certainly only meagre evidence to fill the place of the more complete observations which are needed, but may possibly suffice to make probable what I have stated as my conviction, that the figure is that of the second, and not of the first, archiamphiaster. Perhaps the most noticeable feature of this amphiaster is the inclina- tion of its axis to the supposed animal radius. This specimen is es- pecially interesting, as it is the only one in which I have succeeded in finding evidence of this obliquity. Such a peculiarity has often been noticed by other observers in the case of the first archiamphiaster. It will be’seen from Figs. 53, 54, that the spindle is not radzal in position, The two asters are not of equal extent, the deeper being the larger. Such a difference in sharpness of limitation as I have seen in cther cases is not noticeable here, or at least it is much less marked than in many instances. In neither star does the influence produce rays reaching to the periphery ; in other words, the figure is wholly immersed in the * See page 189. MUSEUM OF COMPARATIVE ZOOLOGY. 207 vitelline substance. This in itself might have been a serious argument against interpreting it as the second archiamphiaster, had I not already shown from Fig. 23 the possibility of such a state of affairs. The MUSEUM OF COMPARATIVE ZOOLOGY. Billy tion to the stellate figures, and that they did not occupy the centres of those figures, but lay somewhat nearer each other (p. 108). After careful examination the author comes to the conclusion that the large nutritive segment is destitute of a nucleus, and therefore refuses to acknowledge that it is a cell. It is only a detached portion of the nutritive yolk. The final paper from Burscuii (’76), portions of the substance of which had already been made public in the two preliminary communica- tions that have been passed in review, embraces a wide field of observa- tion, and presents important additional information upon the phenomena connected with cell division. In the case of Nephelis (p. 219) the stellate figures about the poles of the spindle receive an attention not accorded them in the preliminary papers. Around each of the ends of the first spindle (Richtungsspindel) is to be seen a clear area (Hof), distinguishable from the remaining yolk mass by its homogeneous condition, from which the yolk granules stretch out radially through the yolk in all directions, — “ ein Strahlen- system oder eine Sonne.” The clear area possesses no definite boundary toward the granular yolk, byt merges gradually into it (p. 216). The nucleus of the first segmentation sphere exhibits a distinct, dark envelope (Hiille), and embraces no nucleoli, but instead a clear fluid which is traversed by a number of protoplasmic cords which enclose here and there dark refractive granules, and which are often united into a network. The first segmentation is introduced by an elongation of the yolk and the metamorphosis of the nucleus into a spindle. At each of the oppo- site points of the nucleus which fall in the axis of elongation, there arises in neighboring parts of the yolk a radiation, and at once there begins to appear in the centre of each a clear area of the kind just described. Between these two points the nucleus now begins to undergo a longi- tudinally fibrous differentiation. While this differentiation advances, the still unaltered nuclear remnant continues to exhibit, though less distinctly, its previously described structure, till it at length completely disappears. The volume of such a spindle-shaped metamorphosed nu- cleus is less than that of the original. The change, in Biitschli’s opin- ion, can only be explained by supposing that a portion of the fluid of the nucleus escapes during the metamorphosis. I pass over points already reviewed in the preliminary papers, and only add that Biitschli saw the fibres of the Kernspindel again become thickened and darker in the equator after the beginning of the segmen- tation, and thus form the so-called cell plate of Strasburger (p. 219). 318 BULLETIN OF THE The metamorphosis of the primary segmentation nucleus into a spin- dle was not so satisfactorily traced in the case of Cucullanus elegans. Possibly a stage in this change is represented, says the author, in Fig. 20, where, in place of a nucleus, there is only an indistinctly defined clear spot in the centre of the yolk, within which spot a number of dark granular rods are irregularly disposed. This and all subsequent spindles differ from the “ Richtungsspindel” in that the rods of the nuclear plate in the former lie within a definitely limited body, and cannot therefore be simply a differentiation in the yolk (p. 224), while in the latter the nuclear plate is formed of only a circle of dark granules (p. 226). When the new nuclei have made their appearance in the place of the lateral plates, the nuclear fibres are no longer to be seen. Each nucleus arises from a few (two to four) separate nuclei, which subsequently unite. , pp. 406-410) has described the process by which the germinative vesicle is eliminated from the egg in the case of the trout, and also in that of the hen. (See also Oellacher 70.) By the contractions of the protoplasm of the germ, the vesicle is forced to the free surface, where it becomes ruptured, and, in the case of the trout, its thick wall is spread out on the surface of the germ as a flat, round veil. The contents of the vesicle thus set free appear in the form of one or two finely granular spherules on the MUSEUM OF COMPARATIVE ZOOLOGY. 395 outer surface of the germ. What becomes of them is not known with certainty, though numerous small granules scattered between the sev- mentation spheres at a later stage are thought to have possibly resulted from them. A nucleus was only once seen in the germ before segmentation, and then not carefully studied. He thinks it certainly had no connection with the germinative vesicle, the latter having been already eliminated. Much of the value of Oellacher’s work is due to his employing the sec- tion method with the objects studied. The streaked appearance of the germ as portrayed for two sections (72°, Figs. 27, 28) is of interest as suggesting the persistence of nuclear matter in the germ, and as possibly showing a gyratory tendency in its substance (Fig. 28) not unlike that seen in Limax. Kiernenserc (72, pp. 42, 46, 47), in his well-known paper on Hydra, describes to some extent the regressive metamorphosis of the germinative vesicle, which occurs long before fecundation. The germi- native dot first becomes disintegrated and dissolved. The vesicle is forced to the external pole of the egg, where it undergoes a fatty degen- eration and finally disappears altogether. A contraction of the vitellus takes place soon after the disappearance of the germinative vesicle, and is uniformly accompanied by the elimination of a few particles of the egg substance, which the author identifies with the polar globules* of other animals. No genetic connection between vesicle and polar glob- ules was discovered. Ray Lanxester (’73, p. 85) affirms for Aplysia, that “the germinal vesicle escapes previously to yolk cleavage as the ‘ Richtungsblaschen.’” Notwithstanding his valuable contribution to an intimate knowledge of the nuclear changes during cell division, I think we are justified in presuming that ScHNEIDER (73 p. 113) has overlooked some of the phenomena accompanying the earliest changes of the egg. Biitschli (76, p. 399) with reason questions the propriety of his calling the nucleus of a fecundated egg the germinative vesicle. In this particular case it would seem as though the egg represented by Schneider in Fig. 5. a, Taf. V. embraced still the germinative vesicle, containing, as the * The criticism of Biitschli ("76, p. 384), that the existence of a ‘‘ Pseudozelle (Dotterkern)” in these particles makes it more than probable that they have nothing to do with polar globules, would now be without weight, for it was made at a time when the cell nature of these structures was not understood. The probability that these are polar globules receives also a certain amount of confirmation in the recent studies of Korotneff ("76) on Lucernaria, a review of which is given far- ther on. 396 BULLETIN OF THE latter does, a single nucleolus with a minute fluid-filled space. The most natural explanation of the case would then be, that the spermato- zoa observed and figured within the yolk had not led, up to the time of observation, to a real fecundation;* that the description of the metamorphosis of the ‘‘ germinative vesicle,” as elsewhere (p. 278) given an extenso, relates to that vesicle rather than any other nuclear struc- ture; but that the author overlooked the formation of polar globules, and assumed that the condition of every unsegmented egg found to present some stage of the rosette figure must have resulted ¢mmediately from the metamorphosis of the germinative vesicle, rather than through the intervention of any other nuclear body. The changes of the “ germinative vesicle” of the fecundated egg de- scribed by Fou (’73) for Geryonia have been given elsewhere (p. 279), since they relate to the nucleus of the first cleavage-sphere, not to the germinative vesicle. The metamorphosis of the latter escaped him. The “ Faltenstern ” of the egg membrane is supposed by the author to indi- cate the spot where fecundation takes place; but I think it is more likely that it is connected with the formation of polar globules, of which the author usually saw one.t What that intimate relation is which the polar globule in other ccelenterates sustains to the act of fecundation, the author does not say. One is inclined to believe that he looked for an orifice + owt of which the polar globule had come, and through which the spermatozoa had penetrated znto the egg. BaLBiaNI ('73, p. 84) denies that there exists in spiders any connection between the nuclei of the blastoderm cells and the Purkinjean vesicle. He adds nothing to our knowledge of the metamorphosis of this structure. Burscuui ('73%, p. 101, Taf. XXVI. Fig. 614, 1. —1v.} unquestionably saw and figured what is now known as the female pronucleus, but was unable to give positive information concerning its origin. It makes its appearance as a clear vesicle, at the pole of the egg which is directed toward the vagina, some time after the germinative vesicle has ceased to be visible. Whether the latter is ejected, or simply has become * The observation of unaltered spermatozoa within the yolk gives reason to sus- pect that the egg here figured was not capable of normal development. + ‘‘Vermuthlich entspricht der Faltenstern der Stelle wo die Befruchtung stattfand. Hier befindet sich in der Hiille fast constant ein Korn oder Richtungskérperchen von 15-20 Grésse. Ein ahnliches Kérperchen, welches mit dem Befruchtungsacte in niherer Beziehung zu stehen scheint, habe ich auch bei anderen Coelenteraten beobachtet.” (p. 475.) + “Eine Oeffnung ist beim befructeten Ei hier [i. e. at the Faltenstern] nicht 7 entdecken.”’ MUSEUM OF COMPARATIVE ZOOLOGY. Blvd obscured, Biitschli is unable to say, but evidently inclines to the latter opinion. ScHENK (73, p. 369, Fig. 4) points out the existence of a small cavity in the fecundated eggs of Raja quadrimaculata, which has a triangular outline and opens by a narrow orifice at the surface of the formative yolk. ‘It occupies the place of the germinative vesicle. Vittot (74, pp. 201, 202) informs us that the germinative vesicle has apparently disappeared in the eggs of Gordius at the time of deposit, but the subsequent contractions of the vitellus bring into view a nuclear structure, which he insists is the original vesicle. In his figures (Pl. VII.) he represents only a single polar globule, but says in the text that segmentation is preceded and accompanied (!), as in most animals, by the formation of polar globules, the number, form, and volume of which are variable. In his first studies on Anodonta, FLtemMine (’74, pp. 274-279, Taf. XVI. Figs. 10, 11, 16) traced the appearance of polar globules, but was in doubt as to whether the second of the two bodies resulted from a di- vision of the first one, or was separately eliminated from the yolk. The globules are expelled from the yolk at the pole diametrically opposite the micropyle, and the process is introduced by the appearance of a hyaline margin which in some cases is raised to a knoblike form. This is fol- lowed by the pushing out of a rodlike projection having a conical apex. The formation of the first polar globule is of considerable interest, inasmuch as its production is accompanied by the appearance of short pseudopoda-like projections about the apex of the conical mass. This observation stands without a parallel. The projections, although resem- bling pseudopodia, were never observed to execute rapid motions. A layer of granules in the middle or under the apex of the projecting body is doubtless to be referred to the elements of the external half of the nuclear plate. (Compare spl, Figs. 50, 40, and 67 of Limax.) The yolk was observed to change its form periodically, during this pro- cess of elimination, from a spherical to a more flattened condition, and back again. At this time none of the yolks possessed a nucleus, but. in- stead a “clear place” was to be seen (especially if the egg were subjected to pressure sufficient to flatten it) which was not sharply limited from the rest of the vitellus ; it simply contained fewer and smaller granules than the surrounding yolk; it lay somewhat eccentric, nearer the pole where the globules were eliminated. The polar globules persist only a short time (till the fourth segmenta- tion) ; they stain more intensely than the yolk, and in this Flemming 398 BULLETIN OF THE finds reason for the belief that they take their origin from the nuclear structure, — the metamorphosed germinative vesicle and germinative dot. The second polar globule, however, cannot correspond to the whole of the clear space noticed after the formation of the first globule. In this he is unquestionably right, as the clear space, it will not now be doubted, corresponds to that portion of the first archiamphiaster which is not eliminated with the first-formed globule. The statement by Dreck (74, p. 512) that he has recognized the: ola globules in the case of decapod crustaceans (Maja and Carcinus) is ren- dered comparatively unimportant by the inaccuracy of his ideas concern- ing the nature of those bodies. According to this author the elimination of polar globules — whose discovery he wrongly ascribes to Johannes Miiller — is to be followed in the nemertean Cephalothrix from the first cleavage onward. They are at first large, but afterwards become smaller, in keeping with the diminution in the size of the segmentation spheres. At length they fill a great part of the space between the embryo and the chorion. This confusion of the production of polar globules with abnor- mal processes has already been pointed out by Biitschli. Dieck, however, observed around the germinative vesicle, and around nuclei generally, a clear zone, and during the reappearance of nuclei after each cell division he mentions that it is in this zone that the new nuclei make their ap- pearance. The “zone” probably corresponds to an aster. The unfortunate confusion which LANKEsTER (74, pp. 375, 376, Pl. XVI. Figs. 1-7) experienced regarding the gastrula invagination of Lymneus was due, in part at least, to not carefully distinguishing be- tween the polar globules and the fluid excretions which are so noticeable a feature of the segmentation stages of pulmonates.* In a preliminary note Fou (’74, p. xxxiii.) makes brief mention of the * He says: “They [Richtungsblaschen] may serve a useful purpose for the embry- ologist if they enable him to recognize at any subsequent period when they are pres- ent the original pole at which they made their appearance. But it must be borne in mind that such droplets of albuminous matter are occasionally extruded from eggs of the same character as those of Lymnzus at other points during later stages in the process of segmentation of the egg sphere.”’ I believe there can be little doubt that Lankester’s errors lay in considering the smooth rounded surface shown in his Fig. 4 to be the nutritive or less active pole of the egg, and in admitting the possibility of an inconstancy in the relative position of the polar globules in the case of different mol- lusks. Having often seen corresponding stages in Limax, I am convinced that the active pole of the egg is uppermost in his Fig. 4, as well as in Fig. 7, and that his four ‘large spheres” appear large only because they are very much flattened by the accu- mulation of fluid within. With this explanation there is no serious difficulty in un- derstanding the process of invagination. ————or er -S OE MUSEUM OF COMPARATIVE ZOOLOGY. 399 changes in the Pteropod egg. ‘At the moment of deposit one only sees in the midst of the protoplasm two molecular stars.” After the escape of the polar globules, there appears a nuclear structure (which Fol still insists upon calling a germinative vesicle), which in turn soon disappears, giving place to two molecular stars. This is the beginning of the seg- mentation, as already described for Geryonia. ‘I would only add,” he says, “that I have seen these stars arise in the interior of the germina- tive vesicle, an instant before its diappearance.” The first change in the germinative vesicle of fertilized eggs of Serpula uncinata consists, according to ScHEeNK (’74°, pp. 291 — 294, Figs. 3-8), in its becoming notched. This change is effected by a motion in the granular protoplasm of the yolk, which is directed, as larger and smaller processes, toward the centre of the vesicle. During many passive altera- tions of form the vesicle becomes smaller, and at length reaches the sur- face of the yolk. Here it is for a time distinguishable as a clear space, but finally this fades away till no recognizable trace of it is left. Mean- while the germinative dot is eliminated, and lies between the yolk and its envelope, the latter being raised into a corresponding prominence. This eliminated dot, which is plainly stained in carmine, becomes flat- tened against the yolk, and finally ceases to be visible, the envelope assuming its full circular outline. The changes of the vesicle, but not the elimination of the dot, were also seen in unfecundated eggs. Schenk adds, that one cannot be easily induced to maintain for this structure such a 7é/e as Robin ascribes to his polar globules, since in this case the fate of the germinative dot cannot be further followed, and that he has been unable to observe polar eee either in the case of Ser- pula or Phallusia intestinalis. A sudden contraction of the yolk follows, and afterwards it again fills the membrane completely. The appearance of a stellate figure follows, as described at page 283. Although principally occupied with the events which succeed matura- tion, AUERBACH has contributed much to the understanding of this sub- ject, for he, more than any one else, has fixed the attention of embryolo- gists upon the nature and origin of the first cleavage nucleus, — upon the existence of two nuclear structures which, with Ed. van Beneden, I have designated “pronuclei.” Auerbach (74, pp. 195 et seq., Figs. 1-7) begins the account of his studies on Ascaris and Strongylus with a stage which follows very promptly on the fecundation of the egg. By this epoch of fecundation, however, we are simply to understand a point of time at which the spermatozoa are supposed to come in contact with 400 BULLETIN OF THE the yolk, and he evidently considers the disappearance of the germina- tive vesicle * as a criterion of that event. Besides the entire absence of the germinative vesicle, not the least trace of which could by any means be made visible, this stage is charac- terized by a temporary recession of the yolk granules from the periphery of the egg, during which the vitelline membrane is gradually formed, probably by a condensation of a superfical layer of the protoplasm. The return of the granules to the periphery is immediately followed by the contraction of the whole yolk and the contemporaneous exudation of a quantity of clear iqguor ovi. Thus is completed the formation of the first cleavage sphere, which is throughout homogeneous. As regards the formation of a nucleus in this first segmentation sphere, Auerbach rejected the idea that it appears either as an entirely new centrally located structure, or as a metamorphosed persisting germinative * In the eggs of both these nematodes there is a slight deviation from the truly oval outline ; one end is slightly more obtuse than the other. The more pointed end is characterized, according to Auerbach, by several other peculiarities. It is the one which is in advance as the egg passes through the oviduct, and therefore that which is first exposed to the spermatozoa, probably also the part into which the spermatozoa penetrate. Perhaps this accounts for certain advantages which the narrow seems to possess over the more obtuse end. It is at the former that the polar globules are found ; of the two spheres which result from the first segmentation the more volumi- nous occupies the narrower end ; in its changes this anterior sphere slightly anticipates the hinder one, and is subject to fewer variations from the norm ; and finally, it is this portion of the egg from which the anterior part of the worm is produced. Unfortunately, Auerbach has given no account of the place and manner in which the polar globules are eliminated from the yolk. If their constant appearance at the smaller pole of the egg could be taken as evidence that they were eliminated at that pole, — an assumption which has a certain amount of support in the less granular condition of that end of the yolk (see Fig. 27, Joc. cit.), and in the fact that both pro- nuclei arise at the poles of the vitellus, —then the observation would command par- ticular attention as showing that the almost universal relation of polar globule and first cleavage plane is not in this case maintained. The appearance of the pronuclei at opposite poles of the egg is not easily reconciled with Auerbach’s ideas, for the female pronucleus, we must now assume, makes its ap- pearance near the point where the polar globule arises, and the male pronucleus at the large end of the egg could hardly have arisen from the influence of a spermatozoon penetrating at the smaller. In view of the fact that Biitschli (75, pp. 208, 204) finds the polar globule in non-parasitic nematodes usually at the equator, though sometimes nearer the vaginal pole, and that he has observed its transportation from the place of its origin to the smaller (vaginal) pole, it is perhaps safe to infer that Ascaris and Strongylus offer no exception to the rule that the polar globule makes its appearance in the plane of the future first segmentation, in which event a sub-polar position of the globule would probably correspond to the cases of oblique segmentation so fre- quently observed in the nematodes. MUSEUM OF COMPARATIVE ZOOLOGY. 401 vesicle. He traced its origin from the union of two nuclear structures, which make their appearance at the opposite poles of the egg, and, after attaining their characteristic features, migrate to its centre. After the egg has remained some time in a homogeneous condition, these two structures simultaneously make their appearance as small clear spots close under the surface at each pole. As no difference is recog- nized between them, the further account is the same for both. At first irregular in shape, this spot gradually enlarges and at the same time becomes more nearly circular in outline, until, in the course of half an hour, it has attained its full size and spherical form. It is homogeneous and less refractive than the surrounding protoplasm, from which, although sharply marked off, it is not separated by a membrane. It is a cavity in the protoplasm filled with a substance probably fluid, as may be fairly inferred from the rapid motion of the nucleoli observed later in its his- tory. After a little time there appear within this homogeneous struc- ture from one to five nucleoli, the size of which is generally inversely proportional to their number. Just how they arise Auerbach is unable to say. At first faint, they become darker, and then larger. If numerous, they do not all appear at once, but one after the otlier in intervals vary- ing from half a minute to a few minutes, and at points remote from each other. These two thus fully formed nuclear structures now begin a slow mi- gratory motion toward the centre of the cell, where they finally meet. Meanwhile they suffer no change of form, but the nucleoli within them often exhibit comparatively rapid changes of position. The migration is gradually accelerated. Hach nucleus leaves in its “ wake ” an indication of the course it has pursued, in that the region traversed is less granular than neighboring portions of the protoplasm. The cause of the motion of the nucleoli the author is unable to explain.* The migration of the nu- elei cannot have its cause in any power of motion inhering in the nucleus itself, nor are centres of attraction discoverable ; in fact, any explanation which presumes the protoplasm to be passive can hardly be accepted, since its passive resistance to the motion of the nucleus would cause the latter to become flattened in the direction of the motion. In short, it is the contractile power of the protoplasm which forces onward the passive nucleus, and the clear “ wake” is rather the cause than the effect of this migratory operation. The activity of the protoplasm also finds expres- * Subsequently (p. 247), he ventures the suggestion that it may be due (in case the nuclei increase in size during their migration) to fine streams of fluid (Saftstrém- chen) which must make their way from the protoplasm into the nuclear cavity. VOL. VI.— No. 12. 26 402 BULLETIN OF THE sion during this period of migration in the irregular changes of form which the outline of the yolk undergoes. Assuming that in Auerbach’s observations the female pronucleus is the one making its appearance at the small end of the egg, an occasional variation from the normal method is observable ; for this (female?) pro- nucleus sometimes begins its migration before the male, and therefore meets it between the centre and the blunter pole of the egg. Another variation consists in the occasionally observed origin of the pronuclei at some distance from either pole, in this case, however, usually at diametri- cally opposite points of the surface. The further history of the female pronucleus will be considered under the head of Fecundation. Van Bamsexke (’76, p. 4) has observed that in unfecundated eggs of Tinca vulgaris a spherical portion is sometimes detached during the active changes of form which the germ undergoes, and questions if these are polar globules. The fecundated Pteropod egg, according to Fou (’'75, p. 196), is desti- tute of both membrane and nucleus. It is composed of two parts, for- mative and nutritive, the latter being a network of protoplasm in whose meshes are found nutritive globules. At the centre of the formative part there is a star formed by granules of protoplasm arranged in straight di- vergent lines which extend as far as the limit of the formative part ; the nutritive globules also arrange themselves in lines. After the escape of the polar globules a nucleus appears at the centre (au centre) of the star. The latter. disappears in proportion to the increase in the size of the nu- cleus ; and the granules and globules cease to be in line. In his second paper on the development of Anodonta, FLemmine (75, pp. 109-118) makes some additions to his previous communications on the earliest changes of the egg. The clear spot in the yolk, although less distinct, is visible after the elimination of the polar bodies is com- pleted ; it therefore cannot have corresponded to the second polar globule alone. The latter, at first naked, possesses, after a variable length of time, a membrane. The appearance within it of a large, usually rough, angular, and highly refractive corpuscle, generally attached somewhere to the membrane, is probably a symptom of the death of the globules. The corpuscle and membrane stain more intensely than the contents, “so that one is reminded of a small cell with nucleus, or a nucleus with nucleolus. It would of course in the diagnosis be premature to decide by such a similarity.” The polar globules are found to persist, in @ shrivelled condition, much longer than was at first supposed. MUSEUM OF COMPARATIVE ZOOLOGY. 4038 As Oellacher made considerable advance on his predecessors, owing largely to the use of sections, so Flemming certainly followed rational methods in watching closely the results of staining, and by this means he came near anticipating the later discoveries of Hertwig. As the re- sult of his own observations and those of Oellacher, Flemming insists upon a fundamental importance for the polar globules, principally on account of their constancy and their reaction with staining fluids. Of the manner in which they arise, he still leaves us in doubt. Flemming’s principal objection to considering them the eliminated germinative vesi- cle had been the discovery, at a little later stage, when the radial figures preceding the first cleavage have already appeared (loc. czt., Taf. III. Fig. 2), of a small, deeply staining body (nuclear disk of first segmenta- tion sphere) in the middle of the yolk. Since Fol has deduced a similar nuclear remnant directly from the old nucleus of the egg (germinative vesicle), it is hard to understand, he says, how almost the whole of it (germinative vesicle) should have been eliminated. Auerbach’s discov- eries, however, now come to the rescue, and this “remnant of a nucleus” (Fol) may be supposed to descend from the secondary nucleus (nucleus of the first cleavage sphere), thus leaving no objection to a total elimina- tion of the germinative vesicle. Influenced by the prevailing dogma that the formation of the polar globules is essentially a process of elimi- nation, perhaps a necessary elimination, Flemming naturally raises the question if such does not precede each act of proliferation, — especially since the morphological extinction of the nucleus precedes every division of a segmentation cell, — and, in the absence of any evidence of the elimi- nation of polar globules or their like during segmentation, answers it only by declaring that “ nothing compels the assumption that every pro- cess which characterizes the beginning of the construction of a body must accompany each individual phase of its advance.” The preliminary account given by Butscutr (’'75, pp. 203, 208-210) from studies on several nematodes and two pulmonate mollusks — Lym- neus and Succinea — embraces a valuable contribution toward deter- mining the fate of the germinative vesicle and the origin of.the polar globules. Soon after the eggs of non-parasitic nematodes enter the uterus, the germinative vesicle, having lost its dot, becomes less distinct, and approaches the surface of the yolk, usually at the equator, but some- times nearer the vaginal pole. The surface of the yolk here becomes depressed to receive the clear mass of the vesicle, which lies, as it were, sunk in a pit of the granular yolk. In the case of Tylenchus, as the vesicle reaches the surface a small, round, rather dark body is pushed 404 BULLETIN OF THE out, apparently from the germinative vesicle, and it agrees very closely in appearance with the germinative dot. It is the polar globule. The vesicle appears to sink back into the yolk. In Cephalobus (Anguillula) — the germinative vesicle probably spréads out its substance either zz. or on the clear protoplasm which at this time forms the outer layer of the yolk. Hereby, it is presumable, the nuclear substance subsequently ac- quires a closer relation to the spermatozoon still attached to the surface of the yolk. After the polar globules appear, they are often shoved toward the vaginal or smaller pole of the egg. | . The eggs of Cucullanus are of the greatest interest. Biitschli here makes the discovery of a peculiar spindle-shaped body, which he at once homologizes with the ‘semen capsule” of Infusoria, — a structure arising from the so-called nucleolus. It is hard to say what structure in the fe- cundated egg is homologous with this infusorian nucleolus; he conjectures, however, that it is the germinative dot, and that consequently it is the latter which gives rise to this remarkable structure. In place of the no longer visible germinative vesicle there lies in the yolk, says Biitschli, an elongated, portly, spindle-shaped body of exceedingly interesting constitu- tion. It is two thirds as long as the diameter of the yolk. Its middle is swollen, and its ends are drawn out into fine points. Its mass is darker than the yolk, tolerably homogeneous, often somewhat brilliant, and dis- tinctly and finely fibrous lengthwise. Each of the fibres merges at the swollen middle part into a thick, dark, lustrous portion, which discloses a composition out of serially arranged granules. This spindle is ejected from the yolk, on the surface of which it is seen to lie. But what be- comes of it he is unable to say. From a comparison with the polar glob- ules of the snail’s eggs,* Biitschli conjectures that the two structures (spindle and polar globules) are identical, and that the dark granules and fibres in both cases correspond, although no intermediate stage between the two was discovered. _ | Concerning the origin of the new nuclei of the first segmentation sphere, Biitschli is able to confirm in part Auerbach’s observations, but also to add observations not directly reconcilable with his theories. The nuclei arise in the clear protoplasm of the periphery of the egg, which is accu- mulated at certain points. It is not to be concluded that the nucleus is the result of the metamorphosis of the protoplasm itself, it is formed rather from the material of the germinative vesicle. In Cephalobus rigi- * These appear in the form of two more or less spherical bodies, connected by a stalk, and containing each a disk of granules, the individual grains of each disk being joined to the correspondingly situated grainsf the other by pale delicate filaments. MUSEUM OF COMPARATIVE ZOOLOGY. 405 dus, Rhabditis dolichura, Diplogaster, and Succinea, there appear only two such nuclear structures ; in Cephalobus, at the poles, but not always at the same time ; in Rhabditis, one at the vaginal pole, the other at the point of the surface where the vesicle disappeared, whether the equator or nearer the vaginal pole. The migration and union of these two nuclei, except in Cephalobus, is less regular than Auerbach represents it to be. The amceboid motion of, the yolk at this time is sufficient to explain the mi- gration, but not the coalescence, of the nuclei. In the cases of Rhabditis, Cucullanus, and Lymneeus there are, however, more than two nuclear structures, — from three to eight, or even more, according to the animal. In Cucullanus these arise close under the surface at points remote from each other ; in all cases they are at first quite small, and successively unite till a single nucleus results. In the author’s opinion the formation of the nucleus of the first segmentation sphere by the union of several nuclear structures, since it is of wide-spread or general occurrence, refutes Auerbach’s idea that the whole process results from fecundation taking place at a definite pole of the egg, and the same is shown even more con- clusively by the fact that the nuclei of later generations also arise from the union of several nuclear structures. Gorrte ("75, pp. 20-22) has described the regressive metamorphosis of the germinative vesicle in the case of Bombinator igneus. After approaching the upper (dark) pole of the yolk, it is found to have suf- fered diminution of volume, so that it no longer fills completely the cavity in the yolk which it once occupied. The remaining space of this cavity is filled with a clear fluid. At a later stage there appears at the centre of the dark pole, therefore directly over the vesicle, an irregular yellow spot, which is found, on making sections, to be due to an inter- ruption or obliteration of the pigment layer, which thus allows the un- colored yolk to come to the surface. It is found at the same time that the cavity about the shrunken vesicle has disappeared. Goette | concludes that the former appearance is caused by the escape of the clear | fluid of this cavity, whereby the integrity of the pigment layer is inter- | rupted. There are still some traces of the germinative dots and of the | membrane of the vesicle. A little later there is to be found in place of | the vesicle only an exceedingly fine-granular substance without definite limits. All this takes place before the eggs are laid, therefore indepen- | dently of fecundation. | In freshly laid eggs certain changes in the region of the yellow spot “are to be observed. But only a few of the fresh eggs exhibit all the phenomena. The middle of the spot is often depressed, and sometimes ) } i 406 BULLETIN OF THE presents the same appearance as the button used to upholster a cushion. After a short time the button disappears, and in its place there remains a hole such as arises in making a thrust into a doughy mass. This hole — there may be several of them — may remain till segmentation ensues, or it may disappear earlier. The yellow spot ultimately vanishes. Is not this “button” identical with the spheroidal structures discoy- ered in fishes by Oellacher, and considered by him as the representatives of the polar globules ? Of the results attained by BUrscuii (75%, p. 430) in a second prelimi- nary paper, I will here call attention only to the modification of his views concerning the source of the spindle-shaped body. He now believes it must be considered the metamorphosed nucleus rather than nucleolus, and that in the light of this his previous conclusions are to be correspond- ingly modified. Further details of his paper are given at page 289. SELENKA (75, p. 444) compresses into few words his observations on Phascolosoma elongatum. Some time after fecundation the germinative vesicle disappears, the yolk contracts, and there is pressed out a drop of protoplasm, which he thinks may be the remnant of the “cell nucleus,” — perhaps excrement of the egg. I think it is without doubt a polar globule. Fou’s ("75", pp. 104-108, 198, Pl. I. Figs. 3, 4, Pl. VII. Fig. 2, and ~ Pl. VIII. Figs. 1-3) illustrated paper on the development of Pteropoda, beside giving a summation of results (p. 198) in the words of his prelimi- nary paper, furnishes additional facts of interest, and affords by the fig- ures a better means of judging accurately the nature of his observations. He says the centre of the delicate star which occupies the middle of the formative part of the egg at the time the latter is laid, is not occu- pied, as one might expect, by a corpuscle differing from the surrounding stroma; the granules composing the star also occupy its centre. No activity is to be attributed to the granules themselves ; they are only the landmarks, as it were, of the intimate molecular movements of the proto- plasm which one is unable to observe directly. Some minutes after the egg is laid this star begins to elongate in the direction of the long axis of the egg. It soon divides into two stars, of which one continues to occupy the centre of the protoplasm, while the other reaches the surface in the middle of the protoplasmic area. This point then becomes elevated as a small nipple, and separates itself from the yolk as a spherical globule, for which Fol adopts the term corpuscle excrété, or corpuscle de rebut, as better reflecting than does the term “ Richtungsblischen ” its entire want of significance in the subsequent development. This polar globule MUSEUM OF COMPARATIVE ZOOLOGY. 407 divides into two, usually unequal portions. The escape of two globules, one after the other, was never observed. I think these statements about the division of the polar globules would bear the confirmation of renewed observations. It is the central part of the star which escapes as a polar globule, and the interior of the globules becomes differentiated into protoplasm and nucleus. This last statement, like Flemming’s, appears almost to forestall the work of O. Hertwig, but it will be observed, after all, that there is a wide difference between the differentiation of an excreted corpuscle into nucleus and protoplasm after it is expelled from an egg, and the process of division by which the polar globule is really formed. That which remains of the peripheral star, continues Fol, is little by little mingled with the protoplasm; but the other star, which is more extensive, always occupies the centre of the protoplasm ; z¢s centre be- comes homogeneous, and the star gradually disappears. There arises at the centre of this star a homogeneous corpuscle of slightly less refractive power than its vicinage, whether a vesicle or a more or less solid body is hard to say. Soon two or three similar structures make their appear- ance by the side of the first, and from the fusion of all results the “ ger- minative vesicle” or nucleus of the fecundated egg. Fol figures only one case (Cleodora, Pl. VII. Fig. 2) in which there is more than a single homogeneous corpuscle of this nature, and only two are indicated there, one of which we may safely assume is the male pro- nucleus. From a comparison with his other figures of early stages of Cymbulia, I am almost certain that the nuclear structure (v) represented as occupying the centre of the deeper star in Fig. 2 of his eighth plate is not the female, but the male pronucleus, — in other words, that the aster of which it is the centre has no such genetic connection, as Fol assumes, with the remnant of an aster (a) lying under the polar globule. There are several reasons why it is more consistent to assume that Fol has con- founded these two structures, than to grant that the deep star of the figure referred to is one which took its origin from a division of the first aster. |Special attention had not been called to the different origin of these | nuclear structures, even by those who had observed them ; again, I know of no parallel case where the female pronucleus lies so much nearer the vegetative than the animal pole of the egg; and, finally, I believe this | assumption explains why Fol allows this nuclear structure to occupy the centre of the stellate figure, a thing which can hardly be predicated of . the female pronucleus and its aster before the disappearance of its rays. | 408 BULLETIN OF THE The main objection to this view is the fact that no other complete aster, and no indication of another nuclear structure which might be the female pronucleus, is made to appear in this figure. Ican only assume that the latter was overlooked. As the ovarian egg of Toxopneustes lividus approaches maturity it contains, according to O. Herrwic (’75, pp. 349 — 358), a large spherical germinative vesicle with nuclear membrane derived from the protoplasm, clear contents, and a spherical germinative dot of constant size (13 p) and homogeneous structure. The dot is deeply stained in carmine, the clear contents only feebly. The two are designated as nuclear substance and nuclear juice respectively. Besides these, a network of fine pale fibres stretches through the vesicle, for whose membrane it forms a lining, and is especially concentrated about the dot. In the mature egg found in the oviduct, on the other hand, the germinative vesicle has disappeared without leaving a trace, but there exists a small clear spot which before was not present. The latter is spherical, and 13 w in diam- eter. Intermediate stages lead Hertwig to the conclusion that the vesi- cle is expelled from the egg, that it at first lies in a lenticular depression of the yolk, but afterwards becomes flattened, that its membrane is dissolved and its contents become disintegrated, and probably that it is subsequently absorbed by the yolk. He believes, however, that the _ germinative dot persists without change, and either actively or passively comes to occupy a position in the yolk, as the clear spot already alluded to. The assumption of the identity of the germinative dot with the clear spot (Eikern) is supported in the author’s opinion by equality of size; and by the facts, that both consist of a tolerably firm homogeneous substance without enveloping membrane; that both are stained intensely in carmine and blackened in osmic acid; that the disappearance of, or any change in the dot, could not be observed, nor any steps in the formation of the Kikern; that both structures are never met in the same egg, and never are both absent; and, finally, that the Eikern first appears near the met- amorphosed germinative vesicle, while the dot is last to be seen in imme- diate contact with the surface of the yolk. The necessity of a migration from the vesicle into the yolk cannot be an objection to the identity, since nucleoli have often been observed in amceboid motion. In a general discussion of the topic, Hertwig attempts to harmonize conflicting views, or at least to explain the reasons of such differences. The testimony of those who describe a regressive metamorphosis and disappearance of the germinative vesicle must be accepted as valid for the cases described ; the positive assertions of those who claim that the it | | | | { ee ee Eee eee MUSEUM OF COMPARATIVE ZOOLOGY. 409 vesicle divides and gives rise directly to the nuclei of the segmentation spheres are, however, capable of another explanation, and such cases are therefore not to be considered as exceptions to the ordinary course of events. The trouble lies in the confounding of two entirely different morphological structures, — the germinative vesicle and the egg nucleus (Eikern). The former possesses a firm membrane, fluid contents, and a compact germinative dot ; the latter is without membrane, homogeneous, and without a nucleolus. As it is the latter which has been observed to divide, Hertwig concludes that one may already affirm with certainty that at the maturity of the egg the germinative vesicle as a morphological structure perishes. 'To say how the “ Eikern” originates is more difficult. A cardinal point is touched by the question, Does the egg exist at a definite stage of its development as an enuclear yolk mass, —a cytode? The evidence furnished by those who maintain that such is the case, Hertwig endeavors to weaken, by showing that, although a germinative vesicle could hardly be overlooked, it would be quite easy to pass unno- ticed so small and little differentiated a structure as the germinative dot, —the more, since anything like a satisfactory conclusion can only be reached by having recourse to various reagents, and especially to meth- ods of staining. His own observations have shown conclusively that in some apparently very carefully studied cases a nuclear structure was really present, and had been overlooked by his predecessors. Moreover, in most cases the possibility of the persistence of the germinative dot had not been sufficiently impressed upon the observer to make the observa- tions certain on this point. Even in those cases (Auerbach and Stras- burger) where a direct observation of the origin of the new nucleus is claimed, it is not impossible that a very small germinative dot may have remained unobserved and been in reality the initial stage of the supposed hew structure. The evidence, then, in favor of a new origin for the “ Hikern” is insufficient ; for, on the one hand, it is not established that the egg passes through the cytode condition, and, on the other, the posi- tive statements that the nucleus is a new creation are capable of another explanation. Another error is coupled with this; namely, that fecunda- tion is the cause of the disappearance of the germinative vesicle and of the formation of a new nucleus. “ Der Schwund des Keimblischens und die Entstehung des Hikerns sind vielmehr Vorgiinge, die einzig und allein mit der Reife der Eier zusammenhiangen und die Befruchtungsfihigkeit derselben herbeifiihren.” Finding no entirely insurmountable obstacle in the literature, and sup- ported by his own observations, he draws the general conclusion that “ in 410 BULLETIN OF THE the whole animal kingdom the ‘egg nucleus’ of the mature egg capable of being fecundated arises from the dot of the germinative vesicle which [latter] is dissolved.” | In a paper on the development of fresh-water pulmonates, Rast (’75, pp. 197, 198, 223) adopts Haeckel’s view of the phylogenetic significance of the disappearance of the germinative vesicle; namely, that it is evi- dence that the earliest ancestors of the Gasteropoda, as of all other living organisms, were of the simplest possible structure. The polar globules emerge from the yolk on account of its contractions during the first seg- mentation, and are usually two in number, the first one being the larger. Rabl entertains peculiar ideas concerning their physiological signification. — Since, after a period of quiet, they are uppermost, he concludes that the pole at which they appear is the specifically lightest part of the egg, and that it is safe to assume, inasmuch as they are thus interposed between the egg and the envelope of the albumen, that their function is to protect the egg from pressure. For this reason one must consider these struc- tures protective organs of the embryo acquired through adaptation to the method of unequal segmentation. In Helix at the time of the disappearance of the germinative vesicle, or soon after, there emerge from the yolk, according to Von JHErRiNG (’75, | pp. 303, 304), from one to three polar globules. Whether the vesicle simply perishes, or is ejected, whether or no there is a connection be- tween it and the polar globules, cannot be determined on eggs so unfa- vorable for study. The formation of the globules is proof for the author _of the existence of a vitelline membrane (Taf. XVII. Fig. 2. d). ‘Without contributing any personal observations which bear immedi- ately on the early stages of the egg, Harcken (’75, pp. 421, 426, 434, 435, 446, 480-483) utilizes the preponderating evidence in favor of the disappearance of the germinative vesicle in support of his theory of the palingenetic significance of the cytode stage of the egg, as a “ Riick- schlag der einzelligen Urform in die primordiale Stammform des Mo- neres.” If this atavistic return to the cytode condition should be established for only a part of the animals, but fail for the remainder, then the development in the latter cases would have to be considered as a ceenogenetic process. Lupwie (75, p. 210) was unable to detect any such details in the early stages of the egg of Cheetonotus as have been described by Auer- bach and others, and therefore was only able to say that the germina- tive vesicle disappears entirely while the yolk undergoes contractile changes. MUSEUM OF COMPARATIVE ZOOLOGY. ALT I should not have occasion to call attention here to a paper by Semper (75, pp. 4-13), in which he discusses the origin and nature of the so-called Testazellen of ascidians, were it not for his attempt to identify these structures with the polar globules of other animals, — the less occasion, as his observations relate principally to artificial produc- tions which do not contain nuclei (although the same is true in his opinion for the normally produced “ Testazellen’’) and are only entitled to the name ‘‘ Testatrvopfen.” The reasons given to establish the iden- tity alluded to have proved to be unfortunate, as Whitman (’78") has already pointed out. Nor can Semper’s claim be maintained, that the polar globules “first make their appearance at the moment of segmenta- tion,” * or that they ‘‘are enuclear” ; nor is there any evidence to prove that they are capable of moving themselves in an ameeboid fashion around the embryo. Even though a change in the contour of these globules has often been observed, and the existence of rigid processes which resemble pseudopodia has been demonstrated by Flemming, it is far from proving the polar globules endowed with the power of mak- ing excursions on their own account about the embryo. As Kupffer (70, pp. 123, 124, and 72, p. 366) has shown, the “ Testazellen” appear while the germinative vesicle is still intact, and this is not objected to by Semper, who admits that they arise, not from the nucleus, but from the yolk. The genetic connection of the polar globules with the germi- native vesicle therefore forbids the comparison which he has instituted. But when Semper, partially recognizing the possibilities of such a ge- netic relation, in a foot-note substitutes for an “ Uebereinstimmung in fast jeder Beziehung” a physiological comparison between these two sorts of bodies, he is no longer defending the view already promulgated, | —a view, it is to be observed, which he endeavored to establish with morphological arguments,—but is really supporting new ideas. The physiological dle which Semper discovers in these bodies is ‘the de- tachment of a hitherto integral component of the egg-cell, in some manner a defecation of the same, an elimination of substance apparently useless for the approaching processes.” In a preliminary paper on early stages in the development of the rabbit, Ep. van Benepen ('75, pp. 690 — 693, 695-700) signalizes the | existence of two or three small round bodies (psewdo-nucléoles) and a the polar globules in Physa arise during segmentation will also probably be found to be inaccurate, for it is not consistent with what is known of the nature of these globules in all other investigated animals. H | / { | * P. S. — The recent statement by Brooks (80, p. 79, Pl. I. Figs. 3, 4) that ; | granular substance (nucleoplasma) in the germinative vesicle, in addition to the nucleolus and a clear liquid. The granular substance often as- sumes the form of a network in the growing egg. At maturity the vesicle, instead of being central, becomes superficial, takes an ellipsoidal | form, and then becomes more and more flattened against the zona pellu- — cida. The vitellus is now composed of a medullary mass, and a cortical — layer which becomes clear at the contact of the vesicle. Clear proto- plasm is accumulated around the vesicle in the form of a biconvex lens, —la lentille cicatriculaire, — which depresses the medulla. As soon as the germinative vesicle comes in contact. with the zona, the nucleolus joins the membrane of the vesicle, against which it is flattened and with which it unites ; its plastic substance spreads out into a plate with, at first, a median thickening, — plaque nucléolaire. At the same time the membrane of the vesicle thins out, especially where it is in contact with the cicatricular protoplasm. It is probable that the substance of the membrane is attracted toward, and unites with, the nucleolar plate. The nucleoplasm and pseudo-nucleoli give rise to a mass of granular substance, — corps nucléoplasmique. The liquid and limpid contents of the vesicle mixes with the cicatricular protoplasm upon the rupture of the membrane of the germinative vesi- cle. At the same time the nucleolar plate, by virtue of its inherent contractility, is amassed into a body having sometimes the form of an ellipsoid, often that of a lens; or of a calotte,— corps nucléolaire. At the moment the germinative vesicle disappears, the directive bodies are eliminated. There are two of these, but they are unlike both in compo- sition and signification ; one is the nucleolar body, the other the nueleo- plasmic body. The former is stained in picrocarminate of ammonia, the latter is not. The cicatricular lens becomes granular, and thus indistinguishable from the cortical layer of the yolk. With the disap- pearance of the germinative vesicle begins the retraction of the vitellus, which consists in the expulsion of a transparent liquide perivitellin, and is accompanied by amceboid movements. Subsequently the vitellus resumes its spherical form, and no division into cortex and medulla is visible. In this cytode state the egg is entitled to Haeckel’s designa- tion, “monerula.” All the preceding changes are independent of fecun- dation, and are connected with the maturation of the ovum. In the case of the rabbit they are accomplished within the ovary. Although a portion of what is said in his chapter on the “ Formation of the first Embryonic Nucleus’ pertains to another part of the present review, I shall give it in this connection. Shortly after fecundation 412 BULLETIN OF THE imi ie tt itt MUSEUM OF COMPARATIVE ZOOLOGY. 413 the substance of the vitellus consists of three layers, — superficial, inter- mediary, and central. The second is coarsely and irregularly granular, and more opaque than the other two; the central is clearer, but uniformly granular ; the superficial is almost homogeneous, very refrin- gent, and contains only punctiform granulations. At a point of this outer layer a thickening occurs, and in this point appears a small, round body, which is destitute of granulations and resembles a vacuole ; but in osmic acid this so-called vacuole darkens and assumes a gray tinge, while the vitellus is colored brown. ‘This is the pronucleus périphérique. This sinks deeper into the yolk, at the same time becoming larger, and there appear within it numerous very refringent corpuscles of variable size which resemble nucleoli. In the “central mass” of the egg there appear simultaneously two or three small clear irregular masses, which directly unite into a body with bunched (bosselé) surface. This occu- pies from the first the centre of the egg. It is called by Van Beneden pronucleus central. It differs from the peripheral pronucleus in being considerably larger, and in having a less distinct contour. The two approach till they touch each other at the middle of the yolk. The peripheral pronucleus is spherical, and its contour is regular. The central has the form of a calotte or of a flattened crescent with blunt horns,* its concavity being moulded upon the peripheral pronucleus, from which it is at first separated by central protoplasm sometimes containing several voluminous and refringent granules. In most of the eggs, however, the pronuclei touch or are separated by only an imper- ceptible layer of vitelline protoplasm. The convex face of the central pronucleus is sometimes regular, sometimes lobed, and occasionally divided into two parts in such a manner that there are three conjoined clear bodies. The substances of central and peripheral pronucleus are optically alike, and both exhibit rounded refringent corpuscles of vari- able size, — the nucleoli. The peripheral pronucleus increases rapidly in size, but preserves its spherical form. The central diminishes in volume. They become much less apparent, and at length there exists only one nucleus formed at the expense of the two. Whether they fuse, or one is developed at the expense of the substance of the other, the author is unable to say. This nucleus has an irregular form, indistinct contours, and is composed of a , _ homogeneous substance in which nucleoli are not distinguishable. From the time the pronuclei approach each other in the centre, the vitellus * These eggs were treated with 1% osmic acid, put two or three days in Miiller’s fluid, and then mounted in glycerine. 414 BULLETIN OF THE presents a radiated appearance, which the author does not, however, fur- ther describe. These latter stages are exhibited by unsegmented eggs found in company with eges already divided into two segments, taken from the middle or from the lower half of the oviduct. From all this it is concluded that the first embryonic nucleus is devel- oped at the expense of two pronuclei, one peripheral, the other central. As the spermatozoa have already been shown to become mingled with the superficial layer of the yolk, it is probable that the peripheral nu- cleus is formed, at least partially, at the expense of the spermatic sub- stance. ‘If, as [ think, the central pronucleus is formed exclusively from elements furnished by the egg, the first nucleus of the embryo will be the result of the union of male and female elements.” This latter, however, he expressly states, is only an hypothesis. In the description of the polar globules there is a notable deficiency. Although a fundamental difference is maintained for the two globules, we are not informed of the order in which they make their appearance. In the present state of our knowledge it can hardly be granted that there is any such fundamental distinction between the two as Van Beneden maintains ; it would nevertheless be interesting, and possibly not with- out important significance, to know if in any case there is a noticeable difference in the intensity with which these globules respond to the in- fluence of reagents, especially of staining fluids. For Limax I can only report, without having directed particular attention to the point during my observations, that I have not noticed any constant difference, though I should not wish to assert positively that a more careful study, limited to this single point, would not teach otherwise.* In another direction the studies of Van Beneden are of especial inter- est. I refer to the condition of the two pronuclei, which he has described as a moulding of the central (female) upon the peripheral pronucleus. The possibility of this condition having been produced by the influence of the hardening reagent (osmic acid), does not seem to have occurred to the author. The more I reflect upon it, the more it seems to me this condition may be attributable to the same cause as that which produces similar conditions already described for eggs of Limax treated with the * There are, however, some reasons why it would be difficult to reach entirely con- vincing evidence on this point. A comparison between the first globule of one egg and the second of another would have to deal with unknown individual differences in the eggs, and other possible differences of conditions ; while in a comparison between the two globules of the same egg one could not ignore the possibility of changes (of degeneration) in the older of the two globules which would seriously diminish the value of such comparisons. MUSEUM OF COMPARATIVE ZOOLOGY. 415 same reagent. I will therefore state somewhat more explicitly my con- ception of how this condition may have been brought about. The sudden loss of a quantity of fluid would not be covered by a gradual and uniform shrinkage of the whole nucleus, but would be followed by a giving way of the wall at its weakest point. There is certainly considerable evidence tending to show that that portion of either pronucleus which is directed toward its mate is the one which first shows signs of losing its integrity (compare Limax, I'ig. 70), —is therefore, we may assume, least capable of withstanding external pressure. It would not be surprising, then, to find either of the nuclei yielding first at this point. There are manifest reasons (their close approximation) why the apposed faces would not yield by a movement in opposite directions; the one which, from any cause, exhibited the earlier or stronger tendency to such a change, would entail in its action the corresponding face of its mate. The latter would thus fill the depression caused in the surface of the former. Where the depression in the latter nucleus to balance this out-pushing should occur, would depend, aside from the point of least resistance, upon the direction already given to its substance by the process just described. Thus the pole opposite the eminence already formed would be the point to yield. Although described as successive, these events may nevertheless be con- ceived as simultaneous in their occurrence. Such a conception would, it seems to me, be quite feasible in explaining the shapes presented by the pronuclei in the case of Limax, and at the same time offer a possible ex- planation of the apparent absence of nucleoli. In the case of the rabbit, as described above, however, it is only the central pronucleus which thus suffers an involution. This appears at first to offer an objection to the above explanation, but when one reflects that the central pronucleus is described as being much larger and less conspicuous than its mate, it is possible to believe that this alone is enough to indicate that the central pronucleus may lose much more fluid than does the peripheral. A more Serious obstacle appears to lie in the fact that here the nucleoli probably remain visible notwithstanding this condensation. Moreover, these are not occasional but constant conditions in the approximated pronuclei of rabbits’ eggs, so far at least as can be inferred from the description. If I had been able to reproduce these conditions, even with other reagents than osmic acid, I should be less confident that they represented relations not normal for living pronuclei. Scuuuze’s ("75°, p. 267) excellent paper on the development of Sycan- dra, unfortunately, does not afford much insight into the changes which overtake the germinative vesicle. He believes it disappears, but has not seen any polar globules. 416 BULLETIN OF THE Rosrn ('62, ’62°-7) deserves great credit for having a long time ago called especial attention to the changes which the egg undergoes previous to cleavage. The changes within the cell were, however, incompletely observed, and, though still (1875) maintained, in many particulars funda- mentally wrong. In his more recent memoir on the development of the Hirudinea, Rosin (75, pp. 26-79) has reproduced with slight additions these earlier papers. The description in the one on the formation of the polar globules is of particular interest, as it contains an allusion to a phe- nomenon occasionally seen in Limax, but not hitherto noticed in other animals. Robin says (624, p. 156, Fig. 8, and '75, p. 35, Fig. 10), in describing the formation of the first polar globule in Nephelis: “ At the same time (i. e. during the constriction which rounds off the polar globule) the clear space of the vitelline mass diminishes more and more, until the separation is complete, 07 a plane of division is produced at the junction of the vitellus and the part which is narrowed into the form of a pedicel. This plane of division presents the aspect of a slender grayish or blackish transverse line, and establishes a complete separation between the vitel- lus and its prolongation, which then constitutes a distinct polar globule.” Although this plane does not (in his figures) quite correspond in position to that which in Limax I have ventured to call the cell plate, I have little doubt that it is really the same thing. It seems also in Nephelis — to be only an occasional method of finally terminating the direct connec- tion of yolk and polar globule. Robin has in his recent work (75, pp. 97-105) given a detailed ac- count of the changes which accompany the formation of “ polar rings” in Clepsine, or of such as can be seen on living eggs. As this does not very essentially differ from the account given by Whitman (’78*), I omit a review till it can be given in connection with the observations made by Whitman on the accompanying internal changes, The first chapter of BaLrour’s (’76, pp. 378 — 387, Pl. XV. Fig. 1, and "78, pp. 1-9, Pl. I. Fig. 1) Development of Elasmobranch Fishes is de- voted to the ripe ovarian ovum. Here he concludes that observations in the case of Raja batis, as far as they go, tend to show that the thick membrane of the germinative vesicle is expelled, but that the contents of the vesicle become mingled with the surrounding yolk. He explains (p. 8) how, under certain assumptions, a ‘“ consistent account of the be- havior of the germinative vesicle throughout the animal kingdom” may be framed. “The germinative vesicle, usually before, but sometimes im- mediately after impregnation, undergoes atrophy, and its contents become indistinguishable from the remainder of the egg. In those cases im MUSEUM OF COMPARATIVE ZOOLOGY. ALT, which its membrane is very thick and resistant, —e. g. Osseous and Elasmobranch Fishes, Birds, etc., — this may be incapable of complete resorption, and be extruded bodily from the egg. In the case of most ova it is completely absorbed, though at a subsequent period it may be extruded from the egg as the Richtungskorper. In all cases the contents of the germinal vesicle remain in the ovum.” In a paper on the germinative vesicle and first embryonic nucleus Ep. vAN Benepen (764, pp. 38-76, and ’76°, pp. 153-178) gives a very minute account of the disappearance of the vesicle in Asteracan- thion rubens. Much of this paper is taken up with a comparison of his results in this case and in that of the rabbit, but more especially with a comparison of his own results and those reached by Hertwig in the study of Toxopneustes. We learn here (76%, p. 40) for the first time definitely, that in the rabbit the nucleoplasm with the pseudo- nucleoli forms the second of the two polar globules. He expresses here more positively his conviction that the substance of the central pro- nucleus is absorbed in an endosmotic way by the peripheral pronucleus. The vitellus of the Asteracanthion egg is composed of a clearer, less granular cortical layer with radiated striations, and a central mass which occupies two thirds the diameter of the egg. In the germinal vesicle are to be distinguished the parts already described in the case of mammals: a nuclear membrane enclosing a transparent and perfectly homogeneous liquid ; a germinative spot formed of a very refringent and brilliant substance enclosing a variable number of clear vacuoles ; a reticulum of a finely granular substance (nwcleoplasma) starting out from the germinative spot as a centre and embracing in its substance the pseudo-nucleoli. The latter vary in size and in number (from 8 to 15), and may be spread through the whole vesicle, but usually are situated in the vicinity of the true nucleolus, from which they differ in being much less refractive. , Of nuclei in general Van Beneden holds, that the young nucleus is |formed of homogeneous matter, essence nucléaire. When it enlarges, the jnuclear essence becomes united with a substance (suc nucléaire) taken from the protoplasm of the young cell. The substance nucléaire which results from this union constitutes the body of the nucleus. The mem- brane of the definite nucleus and the nucleoli are unmodified remnants of the primitive young nucleus ; they are formed exclusively of nuclear ‘essence. When a nucleus is about to divide, the nucleoli and the nuclear ‘membrane dissolve in the nuclear substance ; for this reason the contour of the nucleus becomes very indistinct and the nucleoli disappear. After i VOL, VI.— No. 12. 27 } 418 BULLETIN OF THE this solution a complete separation ensues between the nuclear essence, which goes to form the equatorial zone, and the nuclear fluid (swe), which is repelled to the poles of the nucleus. After the division of the zone into two nuclear disks which are to become the new nuclei, this nuclear fluid loses itself in the body of the cell. The vacuoles of the nucleoli are only the result of the momentary union of certain parts of the nuclear swbstance with the nuclear fluid. In the case of the nucleus of the central cell of Dicyema, the use of osmic acid followed by picrocarminate results in giving the nuclear swb- stance a rose color, the nucleolus and membrane a bright red, and in leaving the reticular substance unstained. In the disappearance of the germinative vesicle of Asteracanthion, which takes place in exactly the same manner whether the eggs are fertilized or not, the nucleoplasm and pseudo-nucleoli first disappear, then the dot and the contour of the vesicle become paler, the vacuoles of the dot become confluent, and the surface of the dot gradually be- comes lobed and finally breaks up into a large number of fragments which separate and spread through the whole vesicle. These fragments increase a little in volume, become less refractive, and finally cease to be visible. Some seconds after this the membrane of the vesicle be- comes ruptured on the side toward the centre of the egg and parts of its contents escape; the membrane finally dissolves away, and there remains only a clear spot, with ill-defined and increasingly irregular con- tour. The spot diminishes in size till it vanishes. Van Beneden saw the polar globules * “ formed under his own eyes,” but is unable to give any account of their real origin. All his observations appear to have been made on living eggs, which accounts for his having overlooked many facts. The principal conclusions of VAN BaMBEKE ('76, pp. 99-117), reached by the study of Pelobates, Triton, and Axolotl, have already (p. 389) been stated. It only remains to add that he never observed the for- mation of polar globules, but in eggs of the Axolotl, immersed in alcohol immediately after fecundation, he discovered the existence of a whitish spot at the niveau of, and all around, the fovea germinatiwa, caused by a superficial layer of probably coagulated albuminoid matter, which gradually thinned out toward its periphery. This layer presents in section (Pl. Il. Figs. 5 and 6) a striation perpendicular to its sur * By a double error of translation ‘‘corps directeurs (globules polaires)’” appears in the English translation in the absurd form of ‘distinctive bodies and polar glob- ules,” MUSEUM OF COMPARATIVE ZOOLOGY. 419 face, and is strikingly similar to the veil-like layer seen by Oellacher in the unimpregnated egg of the trout. Van Bambeke, however, objects to Oellacher’s interpretation of this layer, as fur at least as regards batrachians, since in the eggs of the latter the envelope of the germina- tive vesicle never presents the characters pointed out by Oellacher for the trout’s egg. Greerr (76, pp. 34, 35) gives a short preliminary notice of early stages of Asteracanthion rubens. The mature egg has two envelopes : “Gallertzone ” and “Eihaut.” The yolk is composed of a homogeneous — clear ‘‘Grundsubstanz” and two kinds of granules. The germinative vesicle is clear, and has a distinct membrane; the germinative dot is more compact, and embraces small round vesicles variable in number and size. Delicate filaments, stretched through the space of the vesicle, are beset with pearl-like nodules, and exhibit spontaneous motion and branching. After fructification — or without it, if the egg remains a time in pure sea-water — the vesicle disappears, but the germinative dot persists. This, in the fecundated egg, mzgrates like an ameba through the yolk. The latter assumes a radial appearance about the now centrally located germinative dot. The polar globule appears with the first-seg- mentation constriction, or even later. (!) Nothing of a spermatic nucleus was seen, nor are the polar globules to be connected with spermatozoa. GiaRD (76%, pp. 233, 234) traces early changes in the egg of one of the sedentary annelids (Salmacina Dysteri) as follows. After fecunda- tion the germinative vesicle ceases to be visible, and one observes the appearance of a circular, finely granular spot at the surface of the egg, over against which there are two polar globules. The spot in turn dis- appears and the egg suffers a constriction /ess (?) pronounced on the side where the spot was situated. Besides the entire absence of the germinative vesicle in the excluded eges of the spider (Philodromus), Lupwie (’'76, pp. 473, 479) contrib- utes nothing which concerns us in this connection. Strecker (’76°, p. 125) also reports for the eggs of Chthonius that the germinative vesicle — after becoming more elongated, as seen in his figures — entirely disappears, and near the place where it perishes a _ brown round spot, composed of the “coarser granules ” of the proto- ” plasm, makes its appearance. This undergoes division with the subse- | guent total segmentation of the egg. In a chapter first introduced into the second edition of his book on “Zellbildung,” etc., StRasBuRGER (76, pp. 297-305, Taf. VII., VIII.) discusses at some length the question of the fate of the germinative a 420 BULLETIN OF THE vesicle. Led by Hertwig’s studies on Toxopneustes to a re-examination of this topic, he finds the opportunity, with improved methods of treat- ing the eggs of Phallusia, to correct the statement in the first edition to the effect that the mature eggs are altogether destitute of a nucleus, By employing osmic acid on alcoholic preparations, he is able to demon- strate the existence of a structure (Taf. VIII. Figs. 2, 3) which he designates with Hertwig as Eikern. “Dieser Eikern,” says Strasburger, ‘liegt hier der Hautschicht nicht * an, ist derselben oft sogar angedriickt, ausser dem aber von einer helleren Zone umgeben, die aber nicht scharf gegen das angrenzende Protoplasma abgeschieden ist.” I question the accuracy of the conclusion to which Strasburger here arrives. No one has hitherto called attention, I believe, to the possibility of any other interpretation for these figures than that which Strasburger himself gives. Nothing can be further from my purpose than to cast doubt on the persistence of nuclear substance in the egg. It is quite another question if the flattened lens-shaped body represented in Strasburger’s figures 2 and 3 (Taf. VIII.) is really this remaining nuclear substance. The interpretation which I am inclined to give these figures is quite different, and of some importance as bearing on the existence of polar globules in the Tunicata. If, as I have no reason to doubt, Biitschli was right in saying (’76, p. 384) that hitherto nothing had been observed ~ concerning polar globules among Tunicata, this will, in my opinion, be the first evidence tending to show that such bodies are really produced in that group of animals ; for I suspect that these figures represent a stage just prior to the formation of a polar globule. This explanation occurred to me when comparing Fig. 50 (Limax) with Strasburger’s fig- ures. Much the most conspicuous part of Fig. 50 is the areal corpuscle (aa') of the peripheral aster. Were the egg for any reason to become less transparent, it is readily conceivable that all the other parts might become indistinguishable and still leave this flattened oval structure visible, and the surrounding radial system would then appear simply as a less granular or clear zone, a condition of affairs, in other words, which is completely realized in Strasburger’s figures. The features which make it possible for me to maintain the identity of these two structures may be stated as follows :— (1.) The shape of Strasburger’s “ Eikern.” —I know of no case im which the egg nucleus (female pronucleus) exhibits such a remarkable form, — apparently that of a very much flattened biconvex lens of which the thickness is (in Fig. 3) not over one fourth its diameter. * This is evidently a typographical error for ‘‘dicht.” MUSEUM OF COMPARATIVE ZOOLOGY. 4?1 When any considerable deviation from the spherical form of the female pronucleus is noticeable, the latter will, I think, be found to be length- ened rather than shortened along the polar axis of the egg. On the other hand, this flattened condition is quite constant for the corpuscle occupying the centre of the peripheral star of an archiamphiaster.* (2.) The position of the “ EHikern” is such as to make quite improb- able the interpretation given by Strasburger. It is true that, if a polar globule is not formed here as in the majority of animals (viz. by the division of a spindle body), then we have no right to assume the fulfil- ment of all the conditions which obtain in such a process ; but granting for the moment that here as elsewhere a polar globule is thus formed, then the female pronucleus could hardly have the position close to the surface, as given in the figure, much less the position indicated by the words ‘“‘pressed against the Hautschicht.” The constriction which sepa- rates the two unequal cells — polar globule and yolk sphere — divides the spindle figure approximately in the middle. The interzonal fila- ments must be reduced to zero in order to allow the lateral zone of thickenings to form a new nucleus close to or in contact with the thin cortical layer of the yolk. There is abundant evidence that the zone of thickenings which pertains to the polar globule forms a nucleus in, or beyond, the centre of the polar globule, therefore at some distance froin its last formed surface;f and I recall numerous illustrations which place the corresponding parts of the half-spindle remaining in the yolk at an equal or greater distance from its surface,} — none which place the female pronucleus so close to the surface as in the case of Phallusia, if, perhaps, I make an exception of the case of Hippopodius figured by Hertwig.§ If, on the other hand, one takes into account the migration of the spindle as described for Limax, the fact that the corpuscle, aa’, occupies a position close to the surface in the stage represented by Fig. 50, and that it ultimately comes to be fused to the apex of the polar globule (Fig. 63), then the interpretation I have given to Strasburger’s observa- tions will find, I hope, sufficient justification. I will add a single pecu- liarity further, which, though not prominent, may not be altogether insignificant. * Compare for Limax Figs. 43 and 48. See also Whitman’s (’78%, pp. 18-21, Fig. 63. C. P.) account of it as “‘ the pellucid spot.” t Compare for Limax, Fig. 40 ; also numerous figures by Biitschli, 0. Hertwig, and others. ¥ See Biitschli’s figures in Strasburger, op. cit., Taf. VII. Figs. 13, 14. § O. Hertwig, "78%, p. 186, Taf. IX. Fig. 12 (wrongly numbered ‘‘ 9”). 12 BULLETIN OF THE (3.) The surface of the egg in Strasburger’s Fig. 2 is slightly elevated in the region of the questionable corpuscle, somewhat as in Figs. 43 and 50 of Limax. I am well aware that serious objections to this view of the matter may be raised. The entire absence of anything which could answer to the spindle itself, the thickenings of its fibres, or the deeper sun, is at first thought a weighty objection, and yet I can readily believe that in eggs treated first with alcohol these structural peculiarities may have been obscured by the opacity of the yolk, so that only those parts which lay near the surface were distinguishable. Perhaps a more serious ob- jection exists in the probability that the questionable corpuscles were stained by treatment with osmic acid and Beale’s carmine. Strasburger, I believe, does not say directly that such is the case; but even if it was stained, I am not sure that on that account my explanation is to be abandoned. Whitman ('78%, p. 18) says of the “ pellucid spot,” the case of Clepsine, that it is deeply colored with carmine, and he too made use of osmic acid. As far as regards this “ pellucid spot,” I think I have reason to claim that it corresponds with the corpuscle in the centre of the aster of Limax (aqa’), and is not derived from the nuclear plate which Whitman, it is true, did not see, but which could hardly have divided and migrated to the tips of the spindle at so early a stage as is represented by his Fig. 63, or, still less, at the stage of his Fig. 62. So far, then, I have indirect evidence that this flattened cor- puscle may stain in osmic acid, and therefore am able to explain its dark appearance in the figures given by Strasburger. I regret that none of my preparations of this stage were made with osmic acid, as, had they been, I might be able to add direct evidence of the staining capacity of these areal corpuscles. If this explanation be correct, we may confidently expect that the polar globules and their mode of formation will be soon made clear to us in tunicates, and thus one more group of animals be made to lend evidence in support of a rational explanation of the phenomena of matu- ration which shall be applicable to all the higher animals, if not to all organisms. * * P, S.— By the last paper of O. Hertwig (’78%, p. 191) my attention has been called to a preliminary notice by Fol (’77*, p. 339), in which he mentions the exist- ence of two polar globules in the case of Phallusia, that I had entirely overlooked. The oversight was due to the incomplete manner in which the contents were indi- cated on the cover of the magazine in which Fol’s article is published. He has two articles in the October number of the magazine, but his name appears only once on te, eoeteen ee aie ste cere es ME NOE ee A MUSEUM OF COMPARATIVE ZOOLOGY. 48 In his criticism of Hertwig, Strasburger endeavors to show the impos- sibility of accepting the view that the germinative dot persists. Besides the numerous results of other observers which seem irreconcilable with it, a prime objection is, that it leaves no chance for the existence of polar globules, which Biitschli and Fol have connected in their origin with the germinative vesicle. One has only to assume that the half, and not the whole, of Biitschli’s spindle is ejected, the other half remaining in the egg, in order to bring his own (Strasburger’s) observations on the “ canal cells” of conifers into harmony with the results of Biitschli and Fol. For Strasburger (doc. czt., pp. 293-297 and 18-21) makes the very important discovery that in conifers the so-called canal cells present in their formation points of resemblance to the polar globules of animal eggs. After the cell nucleus has remained some time at the end of the ege which is to receive the pollen tube, it is divided a short time before th> fecundation into halves which are at once separated by a ‘“ Hautschicht- platte.” One half, which is accompanied by only a very small amount of protoplasm, becomes the nucleus of the canal cell ; the other half remains in the egg and in migrating from the pole leaves stretched behind it fibres [interzonal filaments], which in turn disappear while the nucleus, increasing in size, advances to the centre of the egg. This is the “ EKikern” (female pronucleus). The formerly expressed idea that the canal cell is a rudimentary structure without recognizable function is to be modified, inasmuch as it is the equivalent of the polar globules, and by its formation the nucleus of the primitive egg (Eian- lage) frees itself of certain ingredients, and thus prepares for the ap- proaching fructification. The protoplasm of the canal cell perishes without function. He also finds the canal cell in Cycas. For mosses and vascular cryptogams, however, only the “‘ Bauchkanalzelle” is to be the cover. Having found the first article, the existence of a second, which occurs some pages farther on, was not suspected. Fol’s description is limited to saying that the polar globules arise after the disap- pearance of the germinative vesicle, and are produced by a process of cell division. As this notice is not accompanied by figures, one is left without the means of definitely confirming or rejecting the opinion I have expressed above about the eggs studied by Strasburger ; the mere announcement, however, that polar globules have been seen, only gives greater probability to my explanation. Since writing the above, I have been able to consult Stossich (77, p. 225), and find that he states, in a criticism of Rabl’s theory of the significance of the polar globules, that he has found these directive vesicles ‘‘in eggs of serpulas, ascidians, and other animals subject to regular segmentation.” This paper antedates that of Fol by some three months, but does not contain any description especially devoted to the formation of polar globules in the ascidians. 424 BULLETIN OF THE considered as the equivalent of the canal cell of conifers. The so-called ‘“‘Fadenapparat ” of the egg of angiosperms has also rightly been held in Strasburger’s opinion to be homologous with the canal cells. Strasburger concludes (pp. 304, 305) that a part of the germinative — vesicle in the animal egg always remains behind, but that this relic does not correspond to the germinative dot. Thus it is more than probable that there is an agreement with corresponding processes in plants, where one half of the divided egg nucleus is eliminated, and the other half is modified in one way or another, and may even become indistin- guishable. : PRIESTLEY (’76) gives a purely objective résumé of the papers of Auer- bach (’74), Strasburger (’75), O. Hertwig (’75), and Van Beneden (’75). GREEFF (’76%, pp. 85-87) takes a position intermediate between Van Beneden and O. Hertwig. He in the main corroborates for Asteracan- thion Van Beneden’s observations, by saying, that the germinative dot first suffers a conversion into granules, that the vesicle then begins to diminish in size and distinctness, and that finally both appear to vanish ; and then he concludes by saying, ‘‘ One cannot positively deny that the germinative spot persists, and, in migrating through the yolk, ameceba-like, becomes so indistinct as to be no longer distinguishable.” He also reports that eggs of A. rubens carefully guarded from fecunda- — tion develop in the normal manner, but considerably slower than fecun- dated eggs (pp. 83-85). SELENKA ("76% p. 167) writes of the freshly deposited eggs of Cucuma- ria, that they no longer possess a nucleus, but exhibit at times “a little drop of protoplasm under the egg capsule,— perhaps the excrement of the egg.” This is probably to be considered the polar globule. “In the course of one or a few hours a clear nuclear area (Kernhof) becomes visible in the interior, in the middle of which arise new nuclei, composed of eight to twenty small bodies (Kernkeime, Goette) united in the form of a mulberry.” Up to a stage consisting of thirty-two segmentation spheres the same peculiar groups of Kernkeime are met with. After- wards the nuclei take the form of smooth balls, destitute of enveloping clear areas. Satensky (76, p. 185, Taf. XIV. Fig. 5) figures an egg of Salpa in which two nuclei [the pronuclei] occupy the opposite poles. I believe Salensky is wrong in holding the presence of these nuclei to be evidence of approaching segmentation. ZELLER ('76, pp. 255 — 260, Taf. XVIII. Figs. 21 — 31) gives an interest- ing account of the processes accompanying cell division, and also some MUSEUM OF COMPARATIVE ZOOLOGY. 425 observations on the maturation of the ovum of Polystomum integerri- .mum. A thickening of the yolk forces the germinative vesicle to one side of the egg, when its section becomes more or less crescentic. The yesicle disappears, leaving behind only a homogeneous light space and faint indications of radiation. The spherical form of the yolk is ex- changed for a more flattened one. Two nuclear structures appear near the surface after the egg has resumed its spherical condition, and unite in the middle of the yolk to form a nucleus which soon disappears. Another case of misinterpretation of the pronuclei similar to Salen- sky’s is that of Barrots (’76, p. 16, Pl. XII. Fig. 2), who says, “ Certain eggs {before segmentation] present two nuclei; they are the nuclei of the first two spheres of segmentation.” Ep. van BenepEN ('76", p. 49) thinks the germs of the infusoriform embryos of Dicyema do not lose their nuclei, as eggs do their germina- tive vesicles, but that the nucleus divides, and thus gives rise to the nuclei of the first two embryonic cells. Bosretzky’s ('76, pp. 97, 98, 100) observations on the stages em- braced under maturation are very limited. At a point on the surface of the freshly laid egg of Nassa mutabilis a small whitish spot is to be seen. Nothing is said about the way the polar globules are formed ; but there are two recognizable with each egg soon after the extrusion of the latter, and they are joined to the egg near the centre of the white spot, by a delicate filament. A nucleus is no longer to be found; once, however, when the polar globules were both formed, the nucleus [female pronucleus ?] could. be distinctly seen immediately under the surface of the ege, but there was no nucleolus; the nucleus was homogeneous, and looked like a vacuole. There is a nucleus-like corpuscle inside the polar globules, which gives to them the appearance of small cells. RaBu gives an account (76, pp. 316, 317, Taf. X. Figs. 4-60), and apparently very accurate figures, of the formation of the second polar globule in Unio, so far, at least, as can be seen on living eggs. _ More than two polar globules were never observed, nor was the second ever produced by a division of the first. The first is usually somewhat larger than the second. He also figures at the vegetative pole a cone- like elevation, which has not entirely disappeared when the second globule is forming. ‘The egg is without a germinative yesicle. In a lengthy consideration of the significance of the polar globules (pp. 331-338) Rabl combats the notion that their elimination is comparable to an act of defecation; for one would then be compelled, he says, to assume quite different physiological processes for the first 426 BULLETIN OF THE stages of development in cases when no polar globules are formed. He then urges in support of his “ protective” theory, — (1.) that, as a rule, _ the polar globules accompany only the “ inequal” method of segmenta- tion; (2.) that the place of their origin is always the animal pole of the germ ; and (3.) that the specific gravity of the animal pole is less than that of the opposite pole in cases of inequal segmentation. From all this Rabl concludes that the polar globules serve the purpose of elastic balls in preventing the dangerous pressure of the germ against the membrane of the egg. For the ascidians with their primordial segmentation, the pressure being uniform on all sides, not a few, but a large number, of these elastic balls (Testazellen) are provided. However ingenious this theory may at first sight appear, it cannot claim to be based upon satisfactory grounds, and I am the more sur- prised that Rabl should have promulgated it in connection with his previous paper on pulmonate mollusks, since in that case such a rela- tively enormous distance intervenes between the “ Eiweisshiille” and the embryo, —a distance so great that one rarely finds the yolk even in the vicinity of the membrane of the albumen until rotation begins, and then, as the author himself admits, this protective function must cease to exist. Apart from the absence of proof that such protection is needed, or is even advantageous to the embryo, or that the polar globules are capable of offering such protection, the links in his chain of argumentation seem to be exceedingly fragile. All authentic obser- vations, it is true, go to show that there exists the constant relation between polar globule and the promorphology of the egg which Rabl has expressed by saying the globule is formed at the animal pole of the germ. That, however, is only the connecting link between two others. I believe the evidence is still wanting to prove that the animal pole of the egg is specifically the lighter in all cases of inequal segmentation, or, at least, that the difference in specific gravity is sufficient to cause the germ to rest with the animal pole uppermost. My own observations in the case of Limax have not afforded the least ground for such a conclusion. The yolks of eggs left undisturbed for hours have been found to present the same want of uniformity in position,which is met with under any other circumstances ; individual eggs have been ob- served for a long time during the early stages of segmentation, the polar globules remaining all the time in such a position as to be seen outside the profile of the yolk. Furthermore, it seems to me, this theory necessitates the assumption that the yolk (or embryo) is specifically lighter than the enveloping medium, otherwise there would be no MUSEUM OF COMPARATIVE ZOOLOGY. AT pressure of the embryo against the membrane directly above it ; but we have not yet the proof that such is universally the case when polar globules exist. The difference in specific gravity will presumably be too little, in most cases, to cause any appreciable pressure in ether direction along the vertical axis. It is, however, quite another question whether polar globules are ccenogenetic phenomena. Rabl certainly deserves credit for having turned the discussion concerning polar globules in a phylogenetic direction, and, unsatisfactory as his protection theory seems, it does not necessarily follow that there is no ground for his claim that the polar globules are comparatively recent acquisitions. If the globules were limited, as he claims, to eggs with unequal segmenta- tion, there would certainly exist good reason to infer that they were in some way adaptive acquisitions of this latter class of eggs. But the following are a few of the many exceptions which make it improbable that polar globules are ccenogenetic adaptations to unequal cleavage ; Hydra (Kleinenberg, "72, pp. 46, 47, 51); Lucernaria (Korotneff, 76, p. 393); Hippopodius, Sagitta, and Echinoderms (O. Hertwig, "787). Indeed, if Strasburger is right in maintaining that the canal cells of conifers, and equivalent cells of both lower and higher plants, are ho- mologous with polar globules, we must apparently go back to a very early point in the history of organisms to discover the origin and true significance of these cells, unless it is assumed they have been separately acquired by the two recognized groups of higher organisms. Rabl has realized the sentiment of Von Baer’s with which he closes | his last paper: “Irrige, aber bestimmt ausgesprochene allgemeine Re- | sultate haben durch die Berichtigung, die sie veranlassen, und die | scharfere Beachtung aller Verhiltnisse, zu der sie nothigen, der Wissen- | schaft fast immer mehr geniitzt, als vorsichtiges Zuriickhalten in dieser Sphare.” StossicH (76) entertains views of the morphology of the egg which } are at variance with well-established information. He is apparently | influenced in his opinion by the study of the germinative vesicle under- | going metamorphosis. | | The egg, he says, is a cell, but the nucleus of this cell is not the’ i germinative vesicle; it is the germinative dot, and within it may be i found the nucleolus. The body of the cell, i. e. the yolk, is composed | of two layers, — an external, adapted to the formation of granules, and an internal (germinative vesicle), homogeneous and hyaline, in which are contained the nucleus and nucleolus. The so-called germinative } e . . . . . . . vesicle is not, in his opinion, a vesicle having a proper membrane, | | 428 BULLETIN OF THE but really an optical effect produced by the differentiation of the protoplasm. If it is not the nucleus of the first segmentation sphere which hag misled the author into denying the existence of a membrane, it must be that he has only seen the germinative vesicle after the beginning of its metamorphosis. If there were previously any chance for doubt, the peculiar spindle shape which both nucleus and germinative vesicle assume now proves sufficiently the morphological equivalency of the two structures. Immediately upon contact with the fecundating element in the case of Serpula the granules of the yolk are much increased, and are seen undergoing a slow rotary motion; this causes an opacity of the yolk which renders the internal layer (germinative vesicle) almost invisible. The latter, therefore, does not disappear, but is simply obscured. This formation of granulations is not simply a mechanical alteration, but is accompanied by a chemical process that eliminates from the yolk certain secondary liquid and gaseous products which accumulate be- tween the yolk and its membrane; it is thus that the yolk becomes somewhat contracted and the membrane much dilated. In consequence of the formation of granulations the external layer of the yolk becomes more dense, and therefore the internal layer (germinative vesicle), being less dense, is obliged to ascend to the surface of the yolk, and thus one pole of the egg becomes clearer than the opposite pole. When the vesicle has reached the superior pole of the egg, the vitelline membrane is resorbed and an aperture formed through which the vesicle escapes in the form of two or three drops, — “directive vesicles,” — which remain between the membrane and the yolk. These directive vesicles only serve to determine the point of departure and the direction of the first cleavage furrow.* The latter is not, however, the first indication of segmentation. After the formation of the directive vesicles the rotary motion of the granules ceases, and they are gradually arranged in two groups between which the plane of division is to pass. The granulations do not remain quite fixed, but are disposed in rays which depart from the centre of each group. Gradually this centre enlarges until it acquires the form of a nucleus, so that the rays produced from the granulations no longer depart from a point, but from a circle. As the furrow of segmentation advances, the rays become more uncertain. * It is an error for Stossich to connect with this view the name of “the distin- guished Miiller, father of embryology,” instead of that of Friedrich Miiller. MUSEUM OF COMPARATIVE ZOOLOGY. 499 Stossich seems to have made, with some other observers, the mistake of confounding the astral areas with new nuclei. Fou (76, pp. 111-113, 188-145, Pl. IV. Fig. 3) describes, but does not very fully illustrate, the phenomena of maturation in the Hetero- pods. “The nucleus had already disappeared in all the eggs (Firo- loides) which I have observed, to reappear before and after the escape of the corpuscules, de rebut.” This statement, with some parts of the immediately following description, is certainly unique. Perhaps the account may be the result of a faulty combination of observations. Fol gives for Pterotrachea the details of the changes, of which the above quotation is an epitome, as follows. The molecular star has the same appearance as in Pteropods. There is, however, this difference, that the protoplasm is so scanty as to form only a thin layer between the nucleus * and the “ protolécithe.” When the nucleus [germinative vesicle ?] has vanished, the vitellus appears composed merely of two very clearly marked spheres set concentrically one within the other. The sphere within is nothing else than the protoplasm, the greatest part, but not the whole, of which surrounds itself with a membrane, and be- comes a central nucleus. At opposite (nutritive and formative) poles of this nucleus there soon appear two centres of attraction whence proto- plasmic rays emerge in all directions [first archiamphiaster]. The stouter of these striations stretch from one centre to the other in the interior of the nucleus. The limits of the latter disappear and the stars move apart. . Biitschli’s fusiform body is only the central part of the vanished nucleus. As to the fibres of the spindle, they are only Striations in the protoplasm. One of the stars approaches the centre, the other nears one pole of the vitellus and there gives rise to the first polar globule. In the interior of the globule is readily to be distin- guished the termination of the spindle fibres (Biitschli), which have their centre at the middle of the exterior extremity of the globule. There enlargements of these strie are also to be observed. The star in the vitellus now divides anew, without having taken the form of a : nucleus. During this division the striations, arranged in the spindle | form, reappear. Then the second globule is formed, in the same man- } * It is often difficult to comprehend Fol’s meaning because he uses the term “nucleus” in the most general sense, when accuracy demands a more explicit term. Here, for example, he speaks of the existence of a nucleus where, to judge from what has preceded (Firoloides and Pteropoda), one has. the right to suppose that the | germinative vesicle has been supplanted by a molecular star, and that consequently | there is no nucleus. | | 430 BULLETIN OF THE ner as the first. After the escape of the [second] polar globule, that which remains of the star approaches again the centre of the vitellus, and becomes rounded in the form of a nucleus. The nucleus not only disappears before each segmentation, but it twzce becomes fused with — the surrounding protoplasm and twice individualized before the first segmentation. In this description that which least coincides with the ideas I have formed from my own observations and those of others is the statement made in the last sentence, together with that which makes the nucleus (germinative vesicle) disappear, and again appear before the formation of the polar globule. Although recognizing the spindle fibres as stouter than the remaining rays, Fol does not admit any fundamental difference between the two. The equatorial thickenings were not seen, and the lateral zones only in the formed polar globule. I have elsewhere stated my reasons for inferring that the changes succeeding the formation of the first polar globule are more complicated than has hitherto been assumed by Fol or any other observer. I wish to call attention to only one or two points in his critical review of other authors and in his “reflexions.” Touching the réle of the nucleus, Fol says: ‘It cannot serve as a centre of attraction pre- siding over cellular division, since these centres of attraction arise at the very limit of nucleus and protoplasm, and since the nucleus, if so be that it is able to persist and divide, would undergo these successive modifications only in.a manner altogether passive, at least as passive as the cell or the segmentation sphere in which it is situated.” And again, ‘‘ Il ne se divise pas, il est divisé.” I believe there are very good grounds for adopting this opinion. The fibres of Biitschli are filaments of sarcode, according to Fol, and the grains (thickenings) are varicosities of the filaments, which have nothing whatever to do with the nucleoli. This is the first paper, I be- lieve, in which Fol admits that the nucleus does not appear to be dis- solved. It changes in volume and appearance, and loses its contour, he says, and its substance obeys the call of the centres of attraction, which, so to speak, tear it in two. Biscuit (76, pp. 215 — 249, 380 — 394, Taf. I. - IV.) contributes val- uable information on the features of maturation in eggs of worms and gasteropods, a part of which was made known in his preliminary account. In Nephelis the youngest eggs studied exhibit near the somewhat flat- tened pole the spindle-shaped body already described, lying with its axis nearly in the axis of the egg. A broad equatorial zone of thickenings MUSEUM OF COMPARATIVE ZOOLOGY. 431 occupies the middle of the spindle. Around each of its ends is a clear homogeneous area, and outside this the yolk granules are arranged in radial lines, thus forming two suns. The “area” passes gradually into the surrounding granular yolk. The spindle is the metamorphosed ger- minative vesicle. It is ejected * from the yolk, not in the simple torm previously described for Cucullanus, but in several vesicular portions which apparently enlarge by swelling up, and are united to each other by narrow necks. The constrictions are due to an active process of nuclear division. Of the three portions of this ejected nucleus (now a polar globule) the first is the smallest, the last the largest. During the early stages of this elimination the part within the yolk retains its spindle form, and a zone of dark granules is found at [near] this end of the spindle, as well as in the part of the polar globule already eliminated. The latter zone is joined by delicate filaments with the filaments within the yolk. Ultimately the whole of the spindle is eliminated. The first and second portions of the polar globules subsequently unite, and a clear vesicle [nucleus] often makes its appearance therein. The female pronucleus was observed at an early stage, but no connec- tion with the spindle was detected. The changes in Cucullanus have already (p. 404) been given. I will add, that Biitschli (doc. cit., p. 224) judges, from the appearance of the optical cross-section of the spindle, that the nuclear plate lies within a definitely circumscribed body, there- fore cannot be a simple differentiation in the yolk. The protoplasm immediately underlying the ejected spindle is for a certain distance clearer and more coarsely granular than the rest of the yolk, from which it is quite sharply defined. This clear protoplasm probably spreads over the surface of the vitellus and is the seat of the formation _ of the new nuclei, since the latter arise close under the surface at widely separated places. * T am not quite satisfied what share Biitschli intends to ascribe to the astral rays in this process of elimination. He says (p. 216): ‘‘ Etwas spatere Stadien zei- gen nun, dass die um das einé Ende des spindelformigen Korpers befindliche Dot- terstrahlung bis in die Oberflache des Dotters geriickt ist und der spindelférmig metamorphosirte Kern sich durch diese Strahlung aus der Oberfliiche des Dotters ' hervorzuschieben beginnt.” I think he has nowhere else intimated that the rays were an agent in the propulsion of a nuclear mass, and it is therefore barely possible | that here he only means to say that the nucleus makes its way through (hindurch) | the peripheral aster. But the more literal reading makes the rays the agent of the | ejection. It is in this sense that O. Hertwig (’77, p. 5) understands the author when | he paraphrases his description by saying : ‘‘Die Kernspindel . . . . wird von einer hier ) | ) 432 BULLETIN OF THE The least intelligible part of the observations on Cucullanus is the total ejection of the spindle in an undiwded state, and its resting intact on the surface of the yolk. This is less likely to be a normal condition of affairs from the fact that stages in the formation of the polar globule quite like those observed in other animals were seen and figured by Biitschli. Observations on several non-parasitic nematodes contribute nothing of special interest concerning the formation of the polar globules, but con- firm the existence of two pronuclei which ultimately become fused. The observations on Lymneus and Succinea confirm the conclusions reached with Nephelis. The earliest eggs studied exhibit a flattened yolk ; one of the poles of the axis thus determined is characterized by a low, broad, conical elevation of clear protoplasm. In the short axis lie two “areas” and their suns, one near the centre, the other nearer the elevated pole, and between the two stretch curved fibres (spindle body). Zones of thickenings do not seem to have been observed till the polar globule was already formed, at least none are figured. This spindle figure migrates toward the surface till one of the ‘“‘ areas” comes to lie in the — surface of the elevated portion of the yolk. This area does not seem to have exhibited any central flattened corpuscle such as Limax shows ; but aside from this and the absence of lateral zones the stage represented in Fig. 2, Taf. IV. of Biitschli’s work corresponds very closely with Fig. 50 of Limax. The polar globule is produced as in Nephelis, but the author thinks he has seen the already formed second globule lying still within the yolk, and joined to the globule already ejected by a slender pedicel, an observation that one cannot now expect to see confirmed. There is some confusion in his mind regarding the persistence of these two sys- tems of rays, apparently resulting from an incomplete conception of the relation of the polar globules to the spindle. The protoplasm found at this pole immediately after the ejection of the first polar globule is lim- ited by a sharp but feebly expressed boundary from the granular proto- plasm of the yolk. I have never seen it so sharply defined as he portrays it in his Figs. 3, 5, and 17, Taf. 1V. It was this feature which helped to mislead the author into the earlier belief that a remnant of the ger- minative vesicle remained behind in a recognizable form. As to the formation of a new nucleus Biitschli says that close under the surface where the polar globules are formed there appear in Lymneous a number (nine or more) of small nuclei close together. Each possesses a distinct dark membrane, and, within the clear fluid contents, a few dark corpuscles with clear centres. The latter adhere closely to the mem- brane. These nuclei melt together, so that at a later stage, although MUSEUM OF COMPARATIVE ZOOLOGY. 433 retaining the same structure, they are fewer and larger. As they in- crease in size, the corpuscles increase in number. At length there are only two large nuclei, and these finally become united. In Succinea there are never more than two, and they may arise far apart. Studies on Rotifera and the pseudova of Aphidz only resulted in show- ing that no elimination took place, although the germinative vesicle un- derwent regressive changes and became indistinguishable. On the streneth of his own observations upon the fate of the germina- tive vesicle, Biitschli comes to the conclusion that it is possible to explain divergences of opinion, and, in particular, that the steps supposed to be preparatory to division are referable to the formation of a spindle and stellar figures, but that this apparent preparation for division never leads _ to that definite end, inasmuch as a process of expulsion supervenes. His belief that only the vesicle was expelled, and that the whole of the spin- dle body suffered this fate, compelled Biitschli to assume that, on the one hand, the extruded mass in certain cases (Nephelis) increased in volume by a process of swelling, and that, on the other hand, the germinative vesicle might suffer a reduction in size by the loss of fluid constituents during its conversion into a spindle. Thus were the differences in volume between vesicle, spindle body, and polar globules to be explained. It is now certainly established by his observations, he thinks, that the Rich- tungsblaschen in snails, nematodes, and leeches represent the ejected ger- minative vesicle, and most likely the whole of it, since none of his obser- vations indicate that any remnant of the vesicle is left behind save the fluid elements which escape at the time of its metamorphosis into a spindle. Biitschli thinks that the structure held by Oellacher to be the radially striate membrane of the germinative vesicle in the trout should not be interpreted in that way; on the contrary, it is a modified portion of the yolk, and is to be considered as the equivalent of the radial striations which have been observed by himself and Fol. Such being the case, the real extrusion of the germinative vesicle occurs later than Oellacher maintains, viz. only after fecundation. Numerous other special cases, which appear to controvert his ideas of the connection of fertilization with the extrusion of the vesicle, he thinks can be explained by the fact | that the vesicle seems to disappear, but really assumes the spindle condi- | tion, and is not actually eliminated before fecundation. In an appendix devoted to a refutation of O. Hertwig’s idea that the germinative dot persists as the “ Hikern,” Biitschli (pp. 432-437) ex- | presses the opinion that this “egg nucleus” may in the case of Toxo- | pneustes represent the whole germinative vesicle, reduced in size after } } VOL. VI.— NO. 12. 28 ii { | ’ t 434 BULLETIN OF THE the disappearance of the dot, or at least a part of it ; but in general one must conclude from his own observations, as well as those of other ob- servers (Strasburger, Flemming), that the nucleus, metamorphosed into — a spindle, is ejected from the yolk. From his own studies he finds no occasion for assuming that this ejection is incomplete. Still, in view of the positive evidence that in conifers a portion of the egg nucleus, as shown by Strasburger, remains behind, he is compelled to admit that he cannot with absolute certainty deny that a part of the nuclear plate of the metamorphosed egg nucleus becomes detached during the elimi- nation to form the basis of one or several of the little nuclei which after- wards appear in the yolk. Two points in his own observations may also be favorable to this view: the origin of the new nuclei in definite spatial relation to the place where the nucleus is ejected, and the ap- parent connection (in Nephelis) of the eliminated egg nucleus with some — of the newly formed nuclei by means of fine filaments. The signification of the polar globules as understood by Biitschli will be further considered in connection with the subject of fecundation. _ Korotnerr ('76, pp. 392-394, Pl. XVI. Figs. 10-13) reports for Lucernaria the existence of a micropyle, which is quite readily seen in fresh eggs. He says it is placed in a depression. It appears as a round clear spot (Fig. 12) when seen from above. The germinative vesicle at the maturity of the egg moves from the interior to the surface. At the same time it takes on an elliptical form and zs peripheral extremity ap- pears to become fused with the vitelline membrane. “ It has appeared to me,” adds Korotneff, “ that the micropyle is always formed at the place of this union.” From the latter part of this description, which I have taken the lib- erty to italicize, I think it is nearly certain that the supposed micropyle is the same as the “ pellucid spot” seen by Whitman, — the corpuscle in the central area of the superficial star of the archiamphiaster. It is peculiar, and perhaps an objection to this view, that the surface of the ego is at this point depressed rather than elevated, yet a like peculiar- ity is to be observed in eggs of Pterotrachea. (O. Hertwig, "78%, p. 208, Taf. XI. Fig. 8.) However that may prove to be, I think this explana- tion will not be found to contravene any of the further observations made by Korotneff, who finds in freshly deposited eggs that a globule * * Korotneff erroneously holds this polar globule to be the expelled germinative dot, just as Lovén and others have long ago done. It is only a typographical error, which here (p. 393) makes Lovell responsible for the idea that the nucleus (instead of nucleolus) escapes as polar globule. MUSEUM OF COMPARATIVE ZOOLOGY. 435 occupies this depression in the surface of the yolk, when only a trace of the germinative vesicle is to be seen (Joc. cit., Fig. 13). The failure to make use of proper reagents is sufficient to explain the absence of every thing relating to the internal appearance of the egg at this time. ScHENK ('77) claims for the germinative dot of Serpula nearly the same function which was ascribed by F. Miller to the ‘ Richtungsbliis- chen.” On a former occasion he did not find polar globules, but instead a flattened body which became pressed into the yolk and ceased to be visible. He now maintains that this structure can be considered the expelled germinative dot, for after fecundation one can follow it from its existence within the germinative vesicle until its complete emergence from the egg. After its exit, it is at first round, and only later becomes flat ; or on the same egg there may be an alternation of these forms. The appearance of this corpuscle is followed by the well-known retrac- tion of the vitellus and the appearance of a radial striation in the pro- toplasm of the egg. This eliminated dot exercises in part the function of polar globule ; it exerts a mechanical or other influence over the yolk which leads to the production of furrows,—an impulse to cleav- age. It is difficult to say whether the dot communicates this impulse through some ‘Impression in den Dotter,” or whether some other stimulus is present. The grounds urged for this opinion do not appear to me of great moment. The elimination of the corpuscle at the point of the surface where the first furrow is soon to appear, and the existence of the cor- puscle in the furrow when the latter does appear, are sufficient to show that accurate observations will make of this corpuscle a polar globule, but not sufficient to give support to the theory here propounded. In a note on fecundation Fou (’77) takes the position that there are two well-marked cases in early stages of development: in one, which is exemplified by the sea-urchin, there is a complete absence of the “ cor- puscule de rebut,” the ovule at the moment of extrusion being already destitute of germinative vesicle and possessing only a female pronucleus ; in the other case, embracing most other animals, the vesicle is replaced by a double stellate figure, one of the stars escapes to form the first polar globule, and the second polar globule may be formed by a division of the first, or, more often, like the first, by the formation of a second double star. The substance thus expelled corresponds to the major part of the germinative vesicle enveloped by a little vitelline protoplasm. The principal difference in these two cases consists in the epoch of the disappearance of the germinative vesicle, whether precocious or tardy. 436 BULLETIN OF THE In a subsequent note Fou ('77") gives the results of recent studies on Asterias glacialis. When the ovule comes into the sea-water the germi- — native vesicle shrivels and in some way melts in the vitellus; its contents do not escape, as Van Beneden thought. The germinative spot also loses its sharp contour, becomes pale, often changes form, continues to dimin- ish, and finally dissolves. Then there remain in the yolk only two ill defined spots, one where the vesicle was located, the other, of ovoid form, approaches the surface. The use of reagents discloses the existence of a double star, which Fol names amphiaster. In its neutral plane this amphiaster often presents bodies of an irregular form which he con- siders as the remnant of the membrane of the germinative vesicle. This is, I believe, the first time Fol records his observation of anything answering to an equatorial nuclear disk.* The remnant of the dot is still visible at some distance from this “ amphiaster de rebut,” but the author “dares not affirm that no fragment of the germinative dot can enter into the composition of this amphiaster.” He afterwards, how- ever, asserts that the female pronucleus has no genetic connection with the nucleolus of the ovule. Fol thinks this first stellate figure (amphzaster) is not yet that which gives rise to the ‘“corpuscules de rebut,” but that it divides within the yolk in such a manner that its peripheral star alone gives rise to the amphiaster which is to be expelled. Thus, it is evident according to his description, that there must at one time be at least three stellate figures in the yolk. May he not have mistaken the star of a male pronucleus for one of these three? At least I see no other explana- tion of this statement, for it is quite improbable that any such division as he indicates really takes place in the first amphiaster. The internal half of the ‘‘ amphiaster de rebut” doubles, and the sec- ond globule is formed like the first ; the internal half of this amphiaster changes into a small spot, and becomes a female pronucleus, which migrates toward, but does not reach, the centre of the yolk. These changes are all effected in the same manner, whether fecundation has preceded or not; if fecundation does not now follow, the egg gradually decomposes. It was never seen to develop parthenogenet- ically. O. Hertwic (77) arrives at important conclusions from studies com- municated in his second paper on “ Bildung, Befruchtung und Theilung des thierischen Eies.” The observations were made on eggs of Hiru- dinea and Rana. To the investigation of the former Hertwig was led by the researches of Biitschli, and undertook their study with the pur- * Consult in this connection pp. 429, 430. MUSEUM OF COMPARATIVE ZOOLOGY. 437 pose of answering three questions which were left by Biitschli in an unsatisfactory condition: (1.) how the germinative vesicle transforms itself into the nuclear spindle ; (2.) whether the fecundation is of in- fluence on the origin of the nuclear spindle and the polar globules; and (3.) whether the nucleus (germinative vesicle) is completely eliminated, or is partly retained and passes into the segmentation nuclei. The ovarian eggs of Hemopis contain a comparatively small germi- native vesicle with membrane in which are found a single nucleolus and accessory nucleoli; the latter are stained deeply in osmic acid and carmine. For this reason they are both to be considered nuclear sub- stance. At maturity the nucleolus divides, and the nuclear membrane dissolves so that there remains in the egg only a clear spot destitute of granules in which parts of the stained nucleolus are observable. One finds in place of this a spindle, which is variously situated, either near the centre of the yolk, or more to one side, and then often with its axis radially placed, one end being at the surface. When centrally located it is surrounded by the same clear area which surrounds the fragments of the nucleolus at an earlier stage. The fibres of the spindle converge in two points, which are sharply expressed in Hertwig’s drawings; they are formed, he says, of compacted nuclear substance, which takes the form of a single dark nucleus (Kern) or several such. This is surrounded by a clear area of protoplasm, around which the yolk granules have a radial arrangement. The middle gone of thickenings becomes especially prom- inent when the egg is treated with reagents. Hertwig considers as stages in the process of the formation of the spindle, (1.) a condition in which there are in the middle of the egg two homogeneous areas close together, around which the yolk granules are arranged in rays, — there being between these two systems a number of dark, coagulated, irrezu- larly formed corpuscles, which have the appearance of nuclear substance; and (2.) a condition in which there is found in place of these corpuscles an indistinctly limited structure of approximately spindle shape, in the middle of which are found small condensed granules not yet arranged into a regular granular disk. From these observations he finds reason to dissent from Biitschli’s view that the spindle is the entire germinative vesicle metamorphosed. He disagrees because of the great difference in the size of these two forms of the nucleus ; the absence of a distinct membrane about the spindle ; and the condition of the egg, so often met with, in which the germina- tive dot or its fragments were the only parts of the vesicle that were preserved. Hertwig does not deny a genetic connection between the 438 BULLETIN OF THE two forms of nucleus ; on the contrary, this connection is supported by the following facts : — 1. They both occupy the same position in the yolk. 2. The clear non-granular area which surrounds the centrally located spindle corresponds very nearly with the size of the germinative vesicle and appears to result from its dissolution. 3. An enuclear condition of the egg, if properly treated, could never be made out. 4. The evidences of the dissolution of the germinative vesicle and the formation of a spindle can be arranged in a continuous series. “At maturity of the egg,” — thus Hertwig summarizes, — “the germi- native vesicle undergoes a series of changes in that its dot breaks up into several pieces, its membrane is dissolved, and the nuclear fluid (Kern- saft) mixes in part with the yolk. These changes are to a certain extent independent of each other, inasmuch as the dot may persist when the membrane is already dissolved, and wce versa. Out of the fragments of the nucleolus and the remnant of the nuclear fluid arises the fibrous spindle- shaped nucleus.” Whether the accessory nucleoli, and whether the whole or only a part of the nucleolus, contribute to this spindle is uncertain. The migration to the periphery of the vitellus may take place in either of the two conditions of the nucleus. The further changes which the excluded egg undergoes within the cocoon were traced on another genus,— Nephelis. The spindle lies already at the time of exclusion in a radial position, with one end near the surface. The first changes are as follows: the rods of the middle zone (Kernplatte) elongate ; the homogeneous areas, especially the pe- ripheral, become larger, and the surrounding rays more prominent and extensive ; the peripheral area is visible in the living egg. Passing over so much as relates to what may be seen on the living egg of the for- mation of the first polar globules, I will enumerate only the internal changes. With the formation of a protuberance of the protoplasm at the animal pole the spindle moves farther and farther from the centre of the egg, for its peripheral tip remains as if attached to the summit of the elevation. The middle zone of thickenings splits into halves, which migrate as in nuclear division generally. The granules remain united by nuclear filaments. In consequence of this, the spindle has increased considerably in length.* It therefore comes to lie, when the pinching * It seems to me that the lengthening of the spindle is very inconsiderable till near the close of the constriction which forms the polar globule, so that it is not quite exact for Hertwig to refer the lengthening of the spindle to any of the preceding MUSEUM OF COMPARATIVE ZOOLOGY. 439 off of the conical protuberance to form the polar globule begins, half in the latter and half in the superficial layer of the yolk. The radiation has meantime diminished, especially in the polar globule, where there is _ to be seen only a very indistinct arrangement of the protoplasm around a dark granule, the peripheral apex of the spindle. I can only confirm for Limax this description, which agrees in every essential particular with what I have seen. In one point, however, I have been less successful than Hertwig. I have not seen the continua- tion of the spindle fibres to the centre of the clear astral area. I observe, moreover, that Hertwig has not uniformly represented the apex of the spindle as occupying the centre of this astral area (e. g. the deep end of the spindle, loc. cit., Taf. II. Fig. 2). Of the lateral zones of thickenings Hertwig adds that they appear, when viewed lengthwise of the spindle, as two circles (not rings) of shin- ing granules. About two hours intervene in Nephelis between the cor- responding stages in the formation of the two polar globules. The changes transpiring during this interval, as I have elsewhere indicated, have hitherto eluded most, if not all observers.* This hiatus in his observations was recognized by Hertwig, for he says (p. 27) this point —the formation of the second spindle — has remained obscure. According to the ordinary course of nuclear division the half of the spindle which remains in the yolk should at first be con- verted into a homogeneous nucleus, and only then elongate. Some of his preparations also seem to favor the justice of this conclusion ; namely, those where the granules of the semi-spindle remaining in the egg had imbibed nuclear fluid and formed small vacuoles. As other intermediate stages were wanting, Hertwig did not feel able to deny the possibility of a completion of the spindle in a more direct manner.f phenomena, especially not to the separation of the halves of the nuclear disk. This is at once evident, I think, from his own figures, as well as from those I have given of Limax. Compare Fig. 40 with Fig. 43. * It is true Fol (77°, p. 448) allows the second spindle to arise by a simple length- ening of the half of the spindle fibres remaining in the yolk, and an elongation of the fibre thickenings; but this conclusion may perhaps not be considered as authoritative and final until it has been shown that intermediate stages cannot have been over- looked. Figures of such intermediate steps as will be a certain guaranty against mistake have not, I believe, been published. There is the more reason for not giving his conclusions too great prominence in this matter, since he affixes so little impor- tance to the spindle fibres, and has in the work just cited figured for the first time in his writings their thickenings. T It may not be quite irrelevant to notice that the intervals which here elapse between the formation of the two polar globules on the one hand, and between the 440 BULLETIN OF THE After the formation of the second polar globule, which somewhat ex- ceeds the first in size, but is otherwise like, and formed like, the first, the half of the spindle remaining in the egg contains a disk of granules, and about its tip a homogeneous area and faint radial striations. A little later a cluster of vacuoles closely pressed together has taken the place of the granules of the disk. These vacuoles are sharply limited from the yolk by a dark lustrous rind having the appearance of nuclear sub- stance, and in the contained fluid small dark granules are suspended. The vacuoles soon increase in size, and flow together into a simple, lobed body, —a nucleus. This female pronucleus migrates toward the centre of the egg, where it meets the male pronucleus. Meanwhile there have appeared in the last-formed polar globule numerous vacuoles in place of the granular zone which occupied its middle. These enlarge and unite into a single vacuole with a dark cortical layer, which stains in carmine. The first-formed globule is partially constricted into two. All three remain attached to each other, and, through the largest one, to the yolk, till about the time of the first cleavage, when they are all combined into a single flattened structure containing three bodies that stain readily. The formation of each polar globule takes place in the manner of a cell division, or, in view of the difference in size of the products, as a cell budding. Hertwig’s studies on Rana are mostly confirmatory of the results reached by Van Bambeke. In the ovarian egg at the time the germi- native vesicle is growing most rapidly it presents a spherical form and complicated structure. There is a membrane and about a hundred nucleoli, which are in contact with its inner surface,* and a rich net- work of finer or broader bands of protoplasmic substance, whose function it is to nourish the nucleoli. The latter are most important compo- nents of the nucleus. Already at the beginning of winter the germina- tive vesicle is found more or less displaced from the centre toward the pigmented pole of the egg, and, although a shrinking in the vesicle takes place, the cavity found outside the vesicle in eggs hardened in formation of the second polar globule and the first segmentation on the other hand, are very nearly the same, so that the production of a ‘‘ homogeneous nucleus” and its conversion into a second spindle cannot be excluded on account of any lack of time for the metamorphosis, provided the changes transpire with the same rapidity as they do in the preparation for the first cleavage. * The nucleoli differ in chemical behavior from the nuclear membrane, with which they do not become fused. In Hertwig’s opinion, therefore, Van Beneden’s view that both are unaltered renmants of the primitive nucleus (i. e. ‘‘nuclear essence ”) is not tenable. MUSEUM OF COMPARATIVE ZOOLOGY. 441 alcohol is an artificial condition, as Bambeke maintains. The shrivel- ling of the vesicle is accompanied by a centripetal migration of the nucleoli. Further changes take place only in the early spring. The vesicle then approaches close to the dark pole, and ultimately exchanges its much lobed and folded outline for that of a flattened curved disk. A pigment zone surrounds this disk, —in R. temporaria even on the superficial aspect, — and is continuous with a pigment stripe extending a short way toward the centre of the yolk. The deep end of this stripe is swollen, and embraces a circular clear space connected with a funnel- shaped similar space immediately under the germinative vesicle. No nuclear structure is to be found in the circular spot. The whole re- sults from the closing together of the pigment zone which surrounded the vesicle when the latter migrated toward the surface, and therefore indicates the course it had taken. The method of the ultimate disap- pearance of the vesicle, which probably takes place about the time the eggs are set free in the abdominal cavity, was not discovered. All the eges from the body-cavity and the oviduct exhibit the same condition, — the peculiar distribution of pigment matter named by Bambeke clav- form figure, and the hemispherical clear mass of yolk at the peripheral end of the latter, but not the least thing, within or without the yolk, that could be considered as a remnant of the germinative vesicle. The vesicle is not eliminated in the Amphibia, as in the trout, but is dis- solved without recognizable remnant, and mingled with the yolk be- fore fecundation. This takes place, however, only after the vesicle has reached the surface. Finally, Hertwig discusses at some length (pp. 68-71) the significa- tion of the polar globules. The three principal sources of confusion in their interpretation have been: (1.) an exaggerated estimate of’ the frequency of their occurrence ; (2.) a mistaken identification of widely different structures, in that every formed particle of protoplasm between yolk and egg membrane has been considered polar globule ; and (3.) the assumption of a genetic connection between two often contemporaneous phenomena, — the disappearance of the germinative vesicle in the mature egg, and the appearance of formed bodies outside the yolk. Since it has been shown that the regressive changes of the germinative vesicle and the metamorphosis of the germinative dot into a spindle-shaped nucleus take place in the ovary a long time before the exclusion of the egos, and that it is only after this that the formation of polar globules takes place, it is evident that the processes stand in no relationship ; they must be separately estimated. 442 BULLETIN OF THE While the phenomena of fecundation are, with slight modifications, the same in all cases studied, the process of maturation is subject, in _his opinion, to greater variation. The simplest method of producing an~ “ego nucleus” from the germinativé vesicle is by a uniform distribu- tion of nuclear substance in the nuclear fluid, and then by a solution of the nuclear membrane, such as appears to take place in conifers accord- ing to Strasburger. With animal eggs, however, the process is more complicated, and there are three methods to consider, of which the simplest is that furnished by Toxopneustes, where the germinative dot persists as “egg nucleus.” With the leeches this is modified by the intercalation of the accessory process of forming polar globules, whereby the nucleolus, instead of becoming a homogeneous “ Eikern,” forms at first a spindle-shaped “ Eikern,” and only indirectly the homo- geneous nucleus. With the amphibians, finally, only a small portion of the nuclear substance — perhaps a single nucleolus — furnishes the diminutive nuclear structure. The last is a modification in the process induced by the mu/ti-nucleolar condition of the germinative vesicle. By studies on Ascaris nigrovenosa Branpt ('77) endeavors to refer all the differences in the appearances presented by the germinative vesicle, its supposed disappearance among others, to an amceboid nature, which induces constant change of form. This Brandt claims can be directly observed. Much of the value which might otherwise attach to his observations is lost from his not having supplemented his work with the proper use of reagents, and from his ignoring the advantages of compression already employed with such success by Auerbach. Brandt goes so far as to express the opinion, that the substance of the germinative vesicle can flow around and envelop the yolk, and that it can assume dendritic forms, become diffuse, disappear, and again collect itself. With regard to the nuclei [pronuclei] discovered by Biitschli and Auerbach, Brandt, although at first incredulous, satisfied himself of their existence ; but instead of arising as minute spots or suddenly as clear balls, they at first present, according to him, the appearance of indistinct, diffuse spots of irregular shape, which, with constant amoeboid change of form, at length become rounded, and then appear most distinct. They are not, however, bodies sw¢ generis, but rather portions of the germinative vesicle that has become parted by ameboid motion, and is thus reconstructing itself. The mutual approach of these pronuclei he explains as being brought about by a change in the position of the pseudopodia ; still the yolk may concur in this move- -- a MUSEUM OF COMPARATIVE ZOOLOGY. 443 ment, especially since a mutual approach of the vesicles is also to be observed while they remain quite spherical. A third cause, he believes, is to be sought in a contractile connecting substance stretched between the two vesicles, in the form of a protoplasmic network, since it is ques- tionable if the contractility of the yolk can effect a regular approach of the vesicles (pp. 371, 379). Finally the latter are completely fused. The germinative vesicle in the egg of the nematode is neither dissolved nor otherwise destroyed. Giarp ('77) gives a description of hyaline spheres which in Rhizo- stoma make their appearance near the surface of the egg, and at its maturity constitute a clear zone just underneath the vitelline mem- brane. As previously (p. 332) stated, he ascribes to Biitschli the discovery that the polar globules are formed in many animals by a process of cell division. With all these animals the excreted corpuscles have the value of rudimentary cells of an atavistic signification,*® and cannot be properly called “corpuscules de rebut.” The latter name is only appropriate for non-cellular material rejected by the vitellus which serves for the formation of accessory organs, the vitelline membrane, for example. It is with the latter that the hyaline vesicles in Rhizo- stoma are to be classed. The results reached by Giarp (’77*) in studies principally on the eggs of Psammechinus miliaris confirm in many points the observations of Fol; in others, his conclusions are different. I shall notice especially their disagreements. The egg of this sea-urchin possesses a very delicate vitelline membrane even before fecundation. A little before maturity the germinative vesicle presents the reticulum characteristic of old nuclei. The nucleolus embraces an irregular nucleolinus. The contents of the vesicle become mingled in an amceboid mass, attain the surface of the yolk, and there are converted into a karyolytic figure. The aster di- rected toward the centre of the egg very rapidly assumes the form of a rounded nucleus, — the structure O. Hertwig took to be the germinative spot. It cannot be the “spot,” for it always appears a little smaller than the latter, and moreover one often encounters eggs in which this Wag- nerian spot is no longer visible, and in which the female pronucleus does not yet present a distinct nuclear aspect. On the other hand, it is inex- act to say that there is no genetic connection between the two (Fol), since the substance of the nucleolus, mingled with that of the germinative vesicle, serves for the formation of the first amphiaster, which gives rise to the female pronucleus. Giard describes the formation of two polar * See also Giard ’76. 444 BULLETIN OF THE globules in non-fecundated eggs soon after their exclusion (less accurately to be traced before exclusion). In the living eggs one sees two eleya- — tions (cumuli) of clear protoplasm, often, though not always, at diametri- cally opposite points of the surface of the yolk. One arises at the expense of the aster which is fellow to that from which arises the female pronu- cleus. This aster forms an inequal karyolytic figure, of which the small aster becomes the cumulus which produces the first polar globale; the second arises subsequently ; both are very small, and disappear quickly, In using staining reagents one finds ¢wo nuclei at this pole of the egg. The more superficial is the one which by dividing forms the polar glob- ules; the other is the female pronucleus. This method of the forma- tion of polar globules is, so far as I know, quite unique. The results published by Fou (’77°) in his paper “Sur le Commence- ment de |’Hénogénie chez divers Animaux,” have been in part given already in the reviews of his preliminary notes. When he says (p. 441) that the internal half of the first “amphiaster de rebut” remaining in the yolk becomes a complete amphiaster, one might possibly be im- clined to infer from the statement that there was some evidence of the conversion of the internal half of the “nuclear plate” into a veritable nucleus as one of the steps in the process of the formation of the second archiamphiaster. This view, however, is entirely unsupported by what — follows. In fact Fol seems to leave no chance for the possibility of such an event, for he says distinctly in this paper (p. 448): “Then the im terior aster is converted into an amphiaster in the following manner. Biitschli’s filaments, instead of retiring toward the centre of the aster, elongate anew, and the varicosities disappear by being drawn out. These filaments again constitute a spindle (Fig. 7), one extremity of which is found at the centre of the internal aster, while the other point of conver- gence for the filaments corresponds to the point of contact of vitellus and first polar globule. In the middle of these filaments new varicosities are formed.” There is nothing in the figure cited, nor in any other of those given by Fol, which fully warrants the name amphzaster, since no trace of a radial influence at the outer pole of the second spindle, save the spindle fibres, is visible, to say nothing of a complete aster at this point. A complete spindle is present ; a complete amphiaster is not. On another point Fol gives (p. 447) somewhat more extensive informa- tion than hitherto. He still insists that with the starfish the first am- phiaster does not give rise directly to the polar corpuscles. “If,” he says, “one treats an egg with reagents a few minutes after the first am- phiaster is formed, one no longer finds an amphiaster, but a compact MUSEUM OF COMPARATIVE ZOOLOGY. 445 body with stellate contour. Does this body correspond to the whole amphiaster, or to only one of its halves? Does it result from a conden- sation or from a division of the amphiaster? The second supposition would appear a priorz the more probable ;* but as I have never suc- ceeded in seeing at the side of this stellate body another aster, I prefer to adhere [?| to the first supposition.” My criticism of the assumption first suggested by Fol — a dwision of the first amphiaster — is perhaps intelligible in the light of his first description. With this statement of facts, it no longer serves as an explanation. I am, nevertheless, still unable to accept the conclusions which Fol has reached on this point, and believe that the phenomena are to be otherwise explained than by assuming that either a division or a temporary consolidation of the first amphiaster normally takes place. Without personal experience with the animal under consideration it is fruitless to attempt any explana- tion. Possibly Fol may have been less certain than he supposed of the relative degrees of advancement presented by the stages compared, and that, after all, the unique stellate body may have represented a condi- tion antecedent to the first amphiaster, rather than subsequent to its formation. The possibility of such an error is not, in view of the necessary use of reagents, entirely improbable. The failure of other observers to distinguish any corresponding stage in the metamorphosis gives reason to think this may be due to an abnormal condition of the eges in which it was seen. Tn living eggs, when the polar globule begins to detach itself, the sur- face of the yolk forms folds arranged like the rays of a star whose centre is the peduncle uniting the globule to the vitellus. These folds become more prominent as the globule detaches itself, and then fade away. This and other phenomena — the elevation of a distinct pellicle in the forma- tion of the polar globules — the author thinks are easily explained, if one admits that the superficial layer of the yolk has a greater consistence than the yolk itself. Although this layer in certain respects deports itself like a true membrane, in his opinion it is not such. There result from the internal half of the second archiamphiaster one or two small clear spots, which present, when treated with reagents, the aspect of young nuclei. They increase in size as they sink into the yolk, and become fused together. Other clear spots appear at the'side of the | first, and they too are fused with it to form the female pronucleus. / Fol also reports the discovery of one (if there are two, the second has | escaped observation) polar globule in the sea-urchin. They are elimi- | * It is the opinion previously adopted. See p. 436. 4 i ’ nated while the eggs are still in the ovary, and are formed as in the star- fish, with the exceptions as to number and as to their failure to raise any sort of a pellicle. On account of the absence of-a pellicle they are soon lost after the exclusion of the egg. The errors of Van Beneden and O. Hertwig relative to the fate of the germinative vesicle are due, in his opinion, to the use of slight pressure, resulting in abnormal phenomena. Other cases (Sagitta and Phallusia) are cited to show that the vesicle may early disappear. In Phallusia the “testa cells” arise within very young eggs and in contact with the nucleus, but this is in no way to be compared with the formation of polar globules, so that the sea-urchin is the only animal whose eggs part with their polar globules while still within the ovary. In Heteropoda after the disappearance of the Wagnerian dot there ap- pear two centres of attraction at the two extremities of the vesicle. The rays of the stars, which announce the existence of these centres, extend partly without and partly within the vesicle. The latter encounter and unite with each other, beginning with those in the middle [axis of spin- dle?], to form the bipolar filaments of the first amphiaster. After the second polar globule is formed, the varicosities of Biitschli pertaining to the last aster reunite with the central mass of the aster to constitute the female pronucleus. The male only makes its appearance when the sec- ond polar globule is forming, notwithstanding fecundation is effected in the oviduct long before. It is at first very small, extremely refringent, and located at the surface of the yolk in a position variable as regards its relation to the polar globules. In the starfish the male aster also re- mains latent up to the same moment. At a certain stage in the growth of both pronuclei there appears a minute nucleolus. The nucleus of the fecundated egg has only a very remote connection with the germi- native vesicle. The figures given by Branpr (77°) to illustrate the formation of the polar globules in Lymnzus cannot be considered as giving a very com- plete idea of the process. In the author’s opinion (p. 591) the globules are formed by a part of the ameboid germinative vesicle swelling forth in the form of a clear rounded drop in which an irregularly outlined nu- cleus at once appears. It is only a portion of the germinative vesicle which is thus expelled, the most of it returning as an ameeboid body into the vitellus, where it becomes indistinct, but still persists, to give origin to the nuclei of the first spheres of segmentation. Brandt’s views of the amoeboid nature of nuclei are elsewhere discussed. O. Hertwic (77%) gives in a preliminary paper the results of studies 446 BULLETIN OF THE _ MUSEUM OF COMPARATIVE ZOOLOGY. 447 on the eggs of a number of animals made in the early part of the win- ter of 1876-77, —therefore very nearly contemporaneous with Fol’s valuable investigations. As the ultimate illustrated papers (Hertwig, "78 and "78"), giving more fully the results on which this preliminary communication is based, have already appeared, I will limit myself here to a statement of Hertwig’s general conclusions, and refer the ‘reader for details to the review of those papers which will be found _ farther on. é ie ‘Hertwig has also discovered, independently of Fol, the existence of polar globules * in Sphzrechinus brevispinosus, which were formed in this case from eggs artificially removed with the ovarium and laid for some time in sea-water. From all his observations Hertwig finds ‘confirmation of his previously expressed views on maturation and fecun- dation, especially in three points: (1.) that the continuity in the __generations of nuclei is not interrupted ; (2.) that the polar globules arise by a process of cell budding; and (3.) that fecundation depends ‘on the copulation of two nuclei. On the other hand, his opinion in Weoard to the prevalence of polar globules is altered. He now believes that a general agreement in this matter throughout the animal king- dom will be established. The most important objective communication in this paper is unquestionably the description given of the method in Phich the first maturation spindle arises in Asteracanthion (see p. 452). _ According to P. Mayer (77, p. 199) the germinative vesicle disap- ears, in the case of Pagurus, while the egg is still in the ovary, so that hen freshly deposited it is “positively enuclear.” Of this he has nvinced himself by crushing the eggs, and has also often observed the origin of a new nucleus. Before it perishes the vesicle is sometimes to be seen near the surface of the egg, — instead of the centre, where it always is at first, surrounded with its protoplasmic area. This | eccentric position he regards as probably abnormal, and indicative of | an approaching disintegration of the egg. With the disappearance of | the vesicle the protoplasmic area surrounding it ceases to exist. For | this reason a direct dispersion of the elements of the vesicle in the pro- _toplasm is the simplest assumption. The protoplasm, retaining its net- like distribution, may subsequently secrete a new nucleus in its centre. Since the existence of a distinct egz membrane (not affected by caustic potash) and of the germinative vesicle appear to exclude each other ; and since fecundation must precede the formation of the membrane, Kg _* The existence of polar globules in the sea-urchins was established by Agassiz | in 1867. See A. Agassiz, '64, p. 6, Pl. I., 77, Daiseelt. cand ‘GF, ps2. 448 BULLETIN OF THE concludes that the vesicle disappears after fecundation, whether as a result of fecundation is uncertain (p. 204). Mayer seems also to have seen in isolated cases of freshly laid eggs a “sort of Richtungsblischen — in process of elimination” ; but he considers this process as also abnor- mal, so that his subsequent suggestion, — that it were, perhaps, not too venturesome to connect this with the eccentric position of the germina- tive vesicle, —has not that importance in his mind which can fairly be attributed to it to-day. | StossicH ('77) has extended his observations to the Hchinoderms, and maintains the same view relative to the morphology of the egg which he previously expressed (76). The germinative vesicle of the’ egg mature and ready for fertilization has a perfectly spherical form, but no membrane; its protoplasm is clear, transparent, homogeneous, and slightly granular. He does not know that Hertwig’s observations of a delicate network within the germinative vesicle have been con- firmed. If it had so complicated a structure, it could no longer be regarded as a cell, but as a much more differentiated organism. The germinative dot always has an eccentric position, is round, and contains a very well pronounced nucleolinus. The author says he has several times had the opportunity of seeing two germinative dots in a single egg. They were, however, always joined ; in these cases the nucleolini were wanting. I do not doubt that these two “germinative dots” are really the conjugating pronuclei, although the accompanying figure (oc. cdt., Tay. I. Fig. 2) gives no evidence of the existence of polar globules or the elevation of the membrane of the egg at any part of the periphery which is shown. After fecundation the nucleolinus is no longer visible, and the con- tours of the dot become always less decided, until they disappear with- out leaving a trace. The vesicle from being round assumes an irregular dentate outline. This change of form is only the effect of a movement developed within the egg by reason of contact with the sperm. Stossich desires his previous hypothesis, that the germinative vesicle approaches the surface in consequence of the greater density of the external layer of the yolk, to be so far corrected as to grant that this is aided by the amceboid motion of the vesicle. He is unable to say whether the whole ‘of the vesicle escapes as the two or three directive vesicles. After the elimination of the last polar globule the yolk be — comes homogeneous, then there is in its centre, after a little time, a round body which becomes more distinct. It is the nucleus of the | 9 MUSEUM OF COMPARATIVE ZOOLOGY. 449 first ‘“‘embryonic sphere,” — the analogue of the germinative dot. Its contour at length becomes less distinct and it entirely disappears. With the dissolution of the nucleus the existence of the first embryonic sphere is at an end, although some minutes later there begin to be developed in the yolk certain phenomena which lead to the formation of two new nuclei and to the division of the yolk into two embryonic _ spheres. The yolk is now homogeneous. Little by little a protoplasmic mass is collected in the centre ; this increases and becomes more readily visible, but its contours are blended ; the granules cease their rotation and are disposed in rays. The central body becomes elongated in a plane perpendicular to that of the polar globules; the motion is not ameeboid ; this nuclear body is divided by a constriction, and afterwards the yolk suffers the same fate. Burscaui (77°, pp. 232 — 237, Taf. XVII.), independently of the recent observations of Hertwig and Fol, radically modified his opinion of the nature of the polar globules. In Neritina fluviatilis he finds that both _ the fertile and the znfertile eggs of a capsule produce polar globules ; the former at least three (only one observation), the latter a larger number, sometimes as many as five. It is not possible, he says, to be certain that all the globules are observed, since in opening the capsule they may easily be lost. Staining in Beale’s carmine and the subsequent well- known method of decoloration by means of hydrochloric acid furnishes evidence that the polar globules are not composed exclusively of nuclear substance, but that they are each composed of protoplasm which encloses from one to three small nucle: ; and, further, that the infertile yolk after the formation of the polar globules still embraces from one to three small nuclei,—#in other words, that a part at least of the germinative vesicle remains in the yolk after the production of the polar globules. Biitschli fully accepts O. Hertwig’s view of the origin and nature of the polar globules, but still from a physiological standpoint thinks their principal signification is to be sought in the removal of a portion of the egg nucleus (germinative vesicle), whether this is accomplished directly or under the form of a “ Zellknospung.” It is probable, he adds, that the infertile eggs have remained unfe- cundated. If this be true, Neritina will afford evidence that polar globules may be produced by unfecundated eggs, a conclusion which Fol and Hertwig have likewise reached from satisfactory evidence. In view of their extensive prevalence, the polar globules are probably of fundamental significance ; their import will receive a sufficient explana- tion only with a more intimate knowledge of the processes of reproduc- VOL. VI.— No. 12. 29 se 450 BULLETIN OF THE tion — especially the phenomena of conjugation—among the lower organisms. A critical review of Biitschli’s “Studien,” etc., by DaLumncER anp DRYSDALE (77), is principally directed to pointing out what is obser- — vation and what inference in Biitschli’s work. HatscHek (77%), without having devoted especial attention to the phenomena of maturation in Pedicellina echinata,. has observed (p. 504) the existence of two or three (?) polar globules of variable size, which are found at the animal pole of that axis which he believes is differen- tiated in the unsegmented eggs of all Metazoa (p. 524). A definitely limited nuclear structure nearer the animal than the vegetative pole (which may be the primary cleavage nucleus) is the centre of a radial arrangement of the yolk elements. The maturation changes of the eggs of Malacobdella and Clepsine have been incompletely observed by Horrmann (77, pp. 18-21, and 77", p. 34). In the former case the germinative vesicle in approaching the surface gradually diminishes in size, but preserves its rounded out- line. ‘Two hours after fertilization two polar globules were seen. With the growth of the egg of Toxopneustes variegatus there appears according to SELENKA (78 and "78“) a remarkable differentiation of the cell into three concentric layers. The middle is a very thin pellucid layer of protoplasm without granules, and disappears when the full size isreached. During the later stages of growth, the outer yolk layer sends out pale pseudopodia, which, at first isolated, arise as blunt or bush-like projections of rapidly altering form, but finally assume the shape of very numerous and fine, motionless rays. These, he believes, serve for the growth of the egg. The whole yolk is undergoing change of form dur- ing the activity of the pseudopodia. Finally it comes to rest, and the pseudopodia are withdrawn. Meantime the germinative vesicle has suf fered changes from its spherical form ; its membrane has been variously folded and wrinkled ; it has approached the periphery of the yolk after the resorption of the germinative dot. Two polar globules are formed. The place of their formation remains a long time recognizable as an elevation of the surface of the yolk (Dotterhiigel). There then appear in the yolk under this elevation several clear bodies which unite to form the “Eikern.” The latter moves inward, but does not take a central position in the yolk. It is probable that the “clear bodies” are the product of a budding (Abschniirung) of the germinative vesicle. The comparison which StrasBuRGER previously ventured to draw be- tween polar globules and the “ Bauchkanalzelle” of the higher crypto- | — MUSEUM OF COMPARATIVE ZOOLOGY. 451 gams and archisperms, makes it of considerable interest to learn the conclusion which he reaches in his more recent studies (Strasburger "77) on the ‘‘ Embryosack” of metasperms. The whole process within the embryo-sac (studied especially in Orchis) is put in a new and unequiv- ocal light. The egg cell, the two “companion cells” (Gehiilfinnen), and the “antipodal cells” (Gegenfiisslerinnen) are all formed, not by a free cell-formation, but by the successive divisions of the cell which forms the beginning of the embryo-sac, and with each division the nucleus undergoes a spindle metamorphosis. From these successive divisions there result eight cells, four in each end of the embryo-sac, or more properly speaking eight nuclei, only six of which (three at each end), become definitely circumscribed cells, since the division is in so far incomplete, that one of the four nuclei in each end of the embryo-sac is left free in the protoplasm of the sac not employed to form the six definite cells. The two nuclei thus left free migrate toward each other and fuse (conjugate?) to form a single nucleus. The group of three cells at the posterior end of the sac are the antipodal cells; of the anterior group, two are the “companion cells,” whose anterior ends form the “ Fadenapparat”’- when it exists, and the remaining one is the egg cell, whose sister nucleus was the anterior of the two copulating nuclei. The “companion cells” cannot be considered equivalent to “canal cells” (or polar globules), since they are not derived directly from the egg cell. The “free” nucleus is the one last to be separated from the nucleus of the egg cell, but its entirely anomalous fate prevents any comparison with canal cells, or, for that matter, with any other, save copulating sexual cells. For the present, then, the angiosperms seem to present no opportunity to extend our knowledge of the possible origin of the polar globules. Notwithstanding this there still remain these important facts, to which Strasburger directs attention, since they show that often parts of the cells which are undergoing sexual differentiation are detached at early stages, and are excluded (like polar globules) from the subsequent sexual act: that in Spirogyra Heeriana a vesicular portion of the cell, which at the time of copulation migrates, is excluded from the copulation (in other Spirogyras, however, this is not the case); that in certain alge, for in- stance, a part of the egg substance is simply ejected, and also that not all of the substance of the antheridium is employed in the formation of the spermatozoids; that in higher cryptogams the “ Bauchkanalzelle” is formed, and the spermatozoids carry about for a time a vesicle which represents a part of the “ Mutterzelle” and which is in no way con- 452 BULLETIN OF THE nected with the fecundation ; and finally, that in the archisperms an equivalent of the “ Bauchkanalzelle” is formed, and that perhaps the separation of the contents of a ‘vegetative cell” in the pollen grains of -archisperms has a preparatory significance for the formation of fecundat-— ing substance. But a difficulty in the way of this view for the spermato- zoids of archisperms is the fact that in Selaginella and other Dichotomese both the “ vegetative cell” and the “ vesicle ” are present. Before the maturity of the egg of Asteracanthion, there is, says O. Hertwie (78), a migration of the germinative vesicle toward the surface of the yolk, where it loses its intra-nuclear network, and where its membrane becomes uneven by reason of infoldings. He recognizes that the germinative dot is composed of two substances, which differ both in the fresh condition and more emphatically when treated with reagents. The smaller portion lies as a protuberance on the larger, or may be entirely surrounded by the latter; it is more promptly and deeply stained, and resists the swelling influence of ammoniacal fluids longer, than the larger portion ; the latter becomes in 2—4% acetic acid quite transparent, while the former becomes intensely lustrous. The changes at the time of maturation are inaugurated in the proto- plasm which surrounds the vesicle. In the living egg it is seen that a knob (Hocker) of protoplasm pushes its way into the germinative vesicle from the side which lies nearest the surface of the yolk. The apex of the knob embraces a light spot free from yolk granules, and sends out long protoplasmic projections in all directions. The nucleolus now (fifteen to twenty minutes after the eggs are brought from the ovary into sea-water) loses its several vacuoles and thus appears homogeneous; in a short time there arises in its centre a larger single vacuole, that is nearly filled by a solid round body, which by the use of reagents is shown to be the same as the above-described smaller portion of the nu- cleolus. Suddenly this vacuole with its contained corpuscle disappears. What becomes of the corpuscle is shown only by employing reagents. The observed stages probably follow each other in this order: the corpuscle lying in the vacuole elongates, becomes pear-shaped, then club-shaped, at length more rodlike, and finally a series of beadlike en- largements. It has thus come to project with its smaller end through the rind of nucleolar substance surrounding the vacuole, and its extrem- ity is at last found to extend into the protoplasmic knob and to occupy — the centre of its stellate figure, This is accomplished in the course of about ten minutes. Then there appear in the centre of the stellate figure granules which consist of nuclear substance and are probably de- MUSEUM OF COMPARATIVE ZOOLOGY. 453 tached from the metamorphosed rodlike body, for the latter ultimately disappears entirely by this process. The granules assume a circular arrangement (I will speak of them as the circle of granules). Hertwig is unable to say positively whether the whole of the other (larger) por- tion of the nucleolus remains in the germinative vesicle, since many preparations favor the view that particles of this portion now make their way into the homogeneous spot of the protoplasmic knob. It at least finally diséppears, as does also the membrane and later the “ Grundsubstanz” of the germinative vesicle. What becomes of the “ circle of granules” Hertwig unfortunately does not state ; also the origin of the second stellate figure and the spindle fibres that unite them cannot be considered as satisfactorily explained by these observations. During the disappearance of the smaller nucleolar body, as seen in living eges, and soon after the début of the first small radial figure, there appears a second like figure near the first. In using acetic acid it is seen that there lies between these two stellate figures a fibrous body whose fibres become more distinct as the remnant of the nucleolus disap- pears. This body ultimately forms the ‘‘Richtungsspindel.”” The latter elongates and takes a radial position, while the asters increase in size. Just what relation the “circle of granules” sustains to this spindle, I am unable to discover. It is a difficult point that needs to be defi- nitely settled. Perhaps the conclusion nearest at hand is that the jibres of the spindle are formed from the outer and larger part of the nucleolus; that the znner corpuscle of the nucleolus furnishes directly, in the ‘‘circle of granules,” the equatorial zone of thickenings. But apparently irrec- oncilable with this supposition is the fact that the “circle of granules” occupies the centre of the first star, and that the second star arises near (not by a division of) the first. The more general conclusion,* and one of fundamental importance, which Hertwig reaches in his preliminary paper ('77% p. 273), seems in the main just, and it is greatly to be regretted that he was not able to * “Wenn ich die geschilderten Befunde deuten soll, so scheint mir ein unverkenn- barer Zusammenhang zwischen dem Auftreten der beiden Strahlensysteme und der & Umbildung des Keimflecks der Art zu bestehen, dass bei der Auflosung des Keimbliis- chens die Kernsubstanz in das Protoplasma iiberwandert und an dem Orte, wo sie ‘sich zu dem Spindelformig differenzirten Kern ansammelt, erst ein und dann das zweite Strahlensystem hervorruft. In erster Linie ist bei dieser Umlagerung der ac- tiven Kerntheile der in der Vacuole des Keimflecks eingeschlossene kuglige Kérper betheiligt. Aber auch von der einhiillenden Kernsubstanz genet offenbar Theile, wenn nicht Alles, in das neue Kerngebilde mit iiber.”’ 454 BULLETIN OF THE settle at the same time the nature of the share each of these nucleolar structures takes in the formation of the maturation spindle. There is, besides, one important point which is not, even in these studies, made sufficiently clear to satisfy me. Iam unable to understand how the sub- stance of the nucleolus is more active in producing the stellate figures than the protoplasm of the yolk. If this radial system is induced by the immigration of nucleolar substance into the protoplasmic knob, then certainly we should not expect the stellate figure before such immigration ; consequently the question must arise, What is the signification of the clear non-granular spot in the protoplasmic knob? Is it not due to the same agency as that which induces the stellate figure? Is it not, in fact, simply the first trace of such a figure still limited in its extent? But this clear spot antedates even that part of the metamorphosis of the nucleolus by which its several vacuoles are succeeded by a single larger subcentral vacuole embracing the smaller nucleolar body (compare Hertwig, "77%, p. 271) ; by so much the more, then, does it antedate the conversion of that smaller nucleolar corpuscle into a rodlike body with its end at the centre of the star. And, further, what shall be said of the “langgestreckte Protoplasmaerhebungen,” ‘‘ which are sent out in the upper wall of the germinative vesicle, raylike, from the apex of the proto- plasmic knob on all sides, like mountain ridges from a central peak”? They are represented in Hertwig’s Taf. VI. Figs. 2 and 3, at a time when the inner corpuscle is entirely enclosed in the vacuole of the nucleolus, and yet the peculiar radial arrangement of these ‘ Erhebungen” can hardly be due to any other cause than that which induces the stellate figure. If the first indication of the commencing metamorphosis is seen in the invasion of the territory of the germinative vesicle by a protuber- ance of the surrounding protoplasm, what can be the necessity of trans- ferring the initiative activity to the nucleolus, which still preserves its morphological integrity? May it not be that Hertwig, by his commend- able exertions in rescuing the nucleus from a position of comparative subordination, has ascribed to this substance undue importance, and given it exclusive control where it is, after all, only one of two co-ordinate factors? A connection there doubtless is between the metamorphosis of the germinative dot and the formation of a nuclear spindle, but it is not so certain that the nuclear substance gives the first impetus to the forma- tion of the stellate figures, which mark, in some cases at least, the first unequivocal steps toward a spindle metamorphosis. When Hertwig speaks of an ‘‘ Ueberwanderung” of nuclear substance into the proto- plasm, I understand that to imply —as in fact his figures in so precise MUSEUM OF COMPARATIVE ZOOLOGY. 455 and satisfactory a manner indicate —a transmigration of recognizable morphological fragments of that substance. If, on the other hand, one were to maintain that dissolved portions of the nuclear substance first escaped the limits of the nucleus (and germinative vesicle), and then were re-collected and thus gave the initiative to the protoplasmic asters, it would be as impossible, with our present means of investigation, to refute as to prove the claim. A short pause ensues — to return to Hertwig’s description — after the formation of the first maturation spindle. The formation of the polar globules follows as in Nephelis. Two points only are of further interest : first, that Hertwig noticed furrows on the surface of the polar globule, as well as of the egg, which converged toward the place of constriction during the budding process, and that the spindle before the formation of the globules becomes broader and shorter. The possibility of an indirect formation of the second maturation spindle, which Hertwig emphasized on a former occasion, neither finds support nor opposition here. The fact that the inner aster has been converted into a “Doppelstrahlung” within a quarter of an hour after the formation of the first polar globule, would seem to preclude the possibility of such an event in the case of the starfish. Nevertheless, I think this point is worthy of still further examination. A zone of granules occupies each of the polar globules; a third, says the author, lies near the surface of the yolk. From the latter is formed _ the egg nucleus, —just how is not quite evident. In the clear space which these granules occupy there appear later a number of vacuoles, and in the centre of each a granule of nuclear substance. The vacuoles soon become confluent, thus forming the egg nucleus, and later the granules are united into a single structure,* —the nucleolus. The egg nucleus has moved during its formation toward the centre of the egg. Hertwig does not say whether the stellate condition which the protoplasm “ nach dem Centrum des Eies zu” has assumed goes in advance of the vacuole or not. It ultimately becomes fainter, and disappears. Hertwig did not succeed in verifying Greeff’s observations of the parthenogenetic development of the starfish. Capers (78, pp. 438-447) has ascertained that, accompanying the metamorphosis of the Ammocetes stage into the adult form of Pe- tromyzon Planeri, the germinative vesicle of the ovarian egg undergoes a very slow migration to the surface of the yolk, and a metamorphosis * In the preliminary paper ('77%, p. 274) it is stated that a single nucleolus arises, after the vacuoles have become confluent, by an ‘‘Ausscheidung.” 456 BULLETIN OF THE from which an egg nucleus (in Hertwig’s sense) arises. The stages of this metamorphosis are not very completely known. Eggs taken between the middle of October and the middle of November from animals ap- proaching maturity exhibit the germinative vesicle, still sharply outlined and already arrived at the periphery of the yolk. Those taken toward the end of November and at the beginning of December, on the contrary, show that the vesicle has already lost its germinative dot and its sharp contour, and only its protoplasm lies in an irregular form at the periph- ery. Within this mass of protoplasm are observable, in the fresh state of the egg, “all sorts of nuclear structures,” which are probably descend- ants of the germinative dot. In many eggs, however, — and these the largest in the ovary, — there was nothing to be seen of a germinative vesicle or nuclear structures ; there was only a clear drop of protoplasm at one point of the periphery. Already, on the 9th of December, the eges of a completely metamorphosed larva exhibited a new nucleus (Hikern) in this clear mass of protoplasm or remnant of the germinative vesicle. Calberla thinks, without having recorded any direct observa- tions of such an act, that a part of the vesicle is eliminated as the polar globule. The new nucleus then migrates toward the centre of the egg, drawing after it a cord of protoplasm destitute of yolk granules. Thus a month or more before the maturity of the egg one finds the following complications of structure. The egg membrane is thickened and exhibits a micropyle at its narrow end where the germinative vesicle approaches — the surface; this he calls an owter micropyle, to distinguish it from the entrance to a canal — “ Spermagang”’ — formed directly underneath it in the granular yolk by the centripetal migration of the egg nucleus and the clear protoplasm it carries with it. The entrance to this latter canal is the inner micropyle. Protoplasm which is destitute of granules en- velops the granular yolk on all sides, and is thickened at this, the animal pole, where it is continuous with the likewise clear protoplasm that fills the “Spermagang.” Within the enlarged deeper end of the latter the egg nucleus lies surrounded on all sides by a stratum of this clear pro- toplasm. GaLeB (78%, pp. 363-366, Pl. XXII. Figs. 1-4) maintains, on much the same ground as the embryologists of ten and twenty years ago, that the germinative vesicle persists, and (without any fibrous meta- morphosis) undergoes a simple elongation, constriction, and ultimate di- vision to form the unequal nuclei of the first pair of blastomeres.* He seems to have taken no measures to insure himself against the possibil- * See also the review at p. 334. MUSEUM OF COMPARATIVE ZOOLOGY. 457 ity of committing the same mistake as the earlier writers, who con- cluded that the germinative vesicle divided because they saw a nuclear structure (which we now know is ot the germinative vesicle) undergo such changes as are here reported. The observations of stellate figures on living eggs are too numerous to allow the acceptance of his con- clusion that they are due to the use of reagents. The figures given by Galeb are interesting in several particulars. His Fig. 3 (Pl. XXIL.) probably shows the pronuclei, which Biitschli figured four or five years ago in a similar situation. Whether it is the germinative vesicle or the female pronucleus which is shown in Fig. 1, it is noticeable that the structure is not in such a position as to warrant the supposition that the polar globules are produced at the equator of the egg, where the first cleavage plane occurs. The position of the globule after its libera- tion would, of course, be of comparatively little value in determining this point, because of the possibility of its passively being made to occupy a position different from that which it had when first produced ; in the case of the female pronucleus or germinative vesicle, however, such a displacement could not be assumed. If future observations directed to settling this point —the mutual relation of the first cleavage plane and the polar globule at the time of its formation — shall show that in some nematodes the globule is formed at the pole of the egg, and that the segmentation plane passes through the equator, it will be nec- essary to seek some explanation of this variation from what now seems to be a very general law. ‘The possibility of a rotation of the yolk after the formation of the polar globules, so that the pole of the yolk comes to occupy the equator of its shell, is not to be lost sight of in this connection. Batrour (78%), after giving a concise account of recent progress in the study of the maturation of the ovum, states some conclusions which he thinks already warranted by the observations (pp. 120-124). The peculiar changes which the germinative vesicle undergoes at the time of maturation are, in part at least, of a retrogressive character. The budding of the polar cells is entirely independent of impregnation. He says further, “I would suggest that in the formation of the polar cells part of the constituents of the germinal vesicle which are requisite for us functions as a complete and independent nucleus * are removed to make room for the supply of the necessary parts to it again by the spermatic nucleus.” From the probable absence of polar cells in cases where par- thenogenesis is most common, he is led to suggest further, “ that a more * The original is not Italicized. 458 BULLETIN OF THE or less essential part of the nucleus 1s removed in the formation of the polar cells ; so that in cases, e. g. Arthropoda and Rotifera, where polar cells are not formed, and an essential part of the nucleus not therefore removed, par- thenogenesis can much more easily occur than when polar globules are formed.” “Tt is possible,” Balfour further observes, “that the removal of part of the protoplasm of the egg in the formation of the polar cells may be a secondary process due to an attractive influence of the nucleus on the cell protoplasm, such as is ordinarily observed in cell division.” RepiacHorr (’78, p. 412, Figs. 1-10) gives a brief account of the structure of the germinative vesicle and some of the changes which overtake it in the case of Tendra zostericola, but reserves an extended account for a future occasion, when his observations shall have been concluded. In the black, round ovarian eggs the vesicle possesses a dis- tinct membrane ; the germinative dot is of irregular form and embraces several irregular vacuoles. When the egg has assumed its peculiar bi- lateral form the vesicle still retains its membrane, and there is then to be found in stained eggs within the germinative vesicle a single, or sometimes two nucleoli, and other spots less deeply stained than the nucleoli, but more deeply than the nuclear fluid. Sometimes it was impossible to find evidence of the existence of a germinative dot in any form. He only hints at the possible fate of the vesicle, and then calls attention to the existence of two polar bodies (“ Excretkorperchen ” ?) differing considerably in size, which were observed in the plane of, and just prior to, the first segmentation. The peculiar growth and activity of the egg of Toxopneustes variega- tus has already been given. SexenKa (’78*) adds in the present paper that in the germinative dot there arise vacuoles, which appear to lead to its complete dissolution ; of this, however, he is made doubtful by the different results obtained by O. Hertwig. He is in accord with Fol and Hertwig as regards the formation of polar globules by the division of a spindle and the re-formation into the “ Eikern” of so much of the latter as remains in the yolk. It is perhaps doubtful if “ pronucleus” is in a morphological sense a proper expression, since neither sperm nucleus nor egg nucleus can alone play the réle of a cell nucleus. While the polar globules emerge, a drop of protoplasm free from granules flows out and soon envelops the whole yolk in the form of a cortical layer endowed with automatic motion. Its fate is threefold : (1.) its outer limiting layer is afterwards elevated as a vitelline mem- brane ; (2.) a part penetrates with the spermatozoon into the “ clear MUSEUM OF COMPARATIVE ZOOLOGY. 459 area” of the first vitelline “sun” (though often observed, this is thought by the author to be without significance) ; but (3.) the greater portion is drawn into the segmentation cavity during the beginning of cleavage, where it helps to form the ‘‘ Gallertkern.” The ‘“ Dotterhiigel ” remains, and with some exceptions the plane of the first segmentation passes through it.* The author agrees with Fol that the vitelline membrane is not pre- formed, but arises with the penetration of the first spermatozodn, and thus offers an insurmountable obstacle to the penetration of other spermatozoa. KupPFFER UND BrEnecke (78, p. 21) maintain that in the case of Petromyzon Planeri and P. fluviatilis there are two polar bodies (Rich- tungskorper) eliminated, one before and one after fertilization. As re- gards the former of these, it was first observed after the retraction of the vitellus,f and therefore its origin and the method of its formation were not observed. It was entirely overlooked by both A. Miiller and Calberla. Kupffer and Benecke say (p. 16) that it gives the impression of a nucleus which is surrounded by a small portion of a coarsely granu- lar mass. Often a distinct nuclear membrane is to be seen, and some- times within it a highly refringent nucleolus ; more often, however, only fragments of a nucleolus. They think it comes from the substance of the disappearing germinative vesicle, either before or during fecundation. It is applied to the inner surface of the watch-glass-shaped elevation of the egg membrane,f but never at the highest point of the dome; and when the micropyle is eccentric, it is found on the side of the dome opposite the latter. The authors combat the view entertained by Cal- berla, that the germinative vesicle gives place to a female pronucleus at the time of the metamorphosis of the ‘“ Ammocetes” into the adult. “‘ Aber diese Auffassung (Calberla’s) verliert allen Boden durch den von uns gefiihrten Nachweis, dass am Beginne des Befruchtungsactes ein Rich- tungskorper eliminirt wird” (p. 20). The proof is not entirely satisfac- tory to me, for I do not see what direct evidence has been produced to show that the supposed polar corpuscle may not have been eliminated from the yolk at a much earlier period than that of fecundation. That it might after elimination become enveloped by the yolk, — which be- fore fecundation fills completely the egg membrane, — and thereby * The signification of this “ Dotterhiigel”’ and its relation to the first plane of segmentation will be discussed hereafter. See p. 499. T See the account given elsewhere (p. 501) of the changes accompanying fertiliza- tion. 460 BULLETIN OF THE escape observation, cannot be considered strange, since similar changes resulting in the obscuration of polar globules have been frequently ob- served. Subsequent statements furnish the only ground presented for such a conclusion. The authors found, namely, on eggs taken from fe- males ready for oviposition, that there was constantly a large, flattened lenticular nucleus near the active pole in the superficial layer of trans- lucent protoplasm. This is comparable, they believe, with the germina- tive vesicle of birds’ eggs, and with that which O. Hertwig has figured for mature batrachian eggs ; it is, however, smaller than the latter, but larger than, and not comparable with, the deeply situated nuclear struc- ture (Kikern) shown by Calberla in his Figs. 3 and 4. This germinative vesicle, from its position and size, just covers the dark spot called by Calberla “inner micropyle.” After fertilization the place of the vesicle is occupied by a clearer mass, but it is difficult to determine its limits on hardened eggs. Before the protoplasmic “ Zapfen” (“ Dottertropfen” of Calberla) dis- appears, one observes that a globular, granular body arises within its previously clear mass, and that it is ejected (second polar globule) from the “ Zapfen” as the latter sinks again into the yolk. In Clepsine the germinative vesicle gives place, according to WHITMAN ('78", pp. 13-49, Figs. 1-9, 60-67), to a bistellate figure, which is called “archiamphiaster,’” while the egg is still in the ovary. The details of the process were not observed. In the earliest stages seen the axis of this archiamphiaster is inclined to that radius of the egg which passes through the centre of the amphiaster, but later this obli- quity disappears, and the axis of the figure coincides with the radius. The most conspicuous parts are the two poles, encircled as they are with well-defined radial lines which extend out into the densely packed yolk spheres some distance beyond the polar “areas.” The central part of the area is more deeply colored with carmine than its peripheral part. Between the two poles is a more or less spindle-shaped space free from yolk spheres. This corresponds very nearly with the germinative vesicle in size. Within this space the radial lines of the two stars are con- tinuous from pole to pole. These interstellate lines appear to differ in no essential way from the other radial lines. In only two preparations was anything found comparable to Strasburger’s Kernplatte, and in these cases of so doubtful a character that they were omitted from the drawings. Whitman is inclined from this to regard with favor Fol’s idea that the spindle fibres are identical with the stellate rays, and only appear different since they are surrounded by different media. The | | | MUSEUM OF COMPARATIVE ZOOLOGY. 461 archiamphiaster is already formed at the time of extrusion, and usually has a radial position with one pole so near the surface that it gives rise toa “polar figure” visible on the living egg as a white spot with dis- tinct radial structure. After the archiamphiaster is formed, the egg, provided it is not extruded and brought in contact with water, may remain in a quiescent condition for at least two (or perhaps for even four or five) days, without any injury or abnormal effect upon its: development. There appears in the centre of the ‘ polar figure” about half an hour after extrusion a minute pedlucid spot which is entirely free from yolk spheres and granules. This is the central part of the polar area of the outer star, and is deeply stained in carmine. I have else- where (p. 421) alluded to the significance of this pellucid spot. Although the subject is not formally discussed by the author, it seems to me that he leaves the impression that he regards this polar corpuscle ‘‘C’. P.” as the beginning of the new nucleus. At least, he says, a similar ‘“ pellucid spot” is seen immediately after the formation of the second polar glob- ule, and marks the place of its exit (p. 20). A section of the egg at this time shows beneath the globules a circular space free from deutoplasm, open toward the globules, and filled with a very fine granular substance, which has the lead-gray tinge characteristic of the germinative vesicle that has been treated with osmic acid. This body, which appears as a pellucid spot on fresh eggs and which may be designated with Van Bene- den and Fol as female pronucleus, says Whitman, is the remnant of the archiamphiaster. Thus indirectly we may infer, I think, that the first-mentioned ‘“‘pellucid spot” was estimated by him to be a nuclear structure. As far as I can judge by comparison with other objects, I am inclined to think that no part of the Kernplatte is embraced in these pellucid spots. I am not so confident that no part of this areal corpus- cle enters into the composition of the female pronucleus in the case of Clepsine. To judge from what takes place in Limax, it is to be ex- pected that this corpuscle in the polar cells, at least, takes no part whatever in the nuclear structure. If it shall hereafter be possible at any time to trace the fate of the Kernplatte, the question may be defi- nitely settled ; till then I can only believe that there is no essential variation in Clepsine from what I have seen in Limax. The formation of the polar globules in C. marginata is accompanied by a very interesting change in the form of the egg, first observed by Whitman. About thirty minutes after extrusion a marked constriction of the egg at the equator becomes visible ; this constriction without be- coming very deep advances slowly and uniformly toward the pole where 462 BULLETIN OF THE the pellucid spot is located. In from ten to fifteen minutes it is com- pleted, leaving only a nipple-like protuberance from which the first polar globule begins to emerge. “That part of the polar globule first to appear is perfectly transparent, but the half last eliminated is filled with. minute, highly refractive granules, the outer border of which forms a straight line at first.” After its elimination, the yolk, which had re- ceded from the vitelline membrane at the formative pole of the egg; again fills out the perivitelline space coming in contact with the mem- brane, and thus the polar globule is pushed so far back into the yolk that it is seen with difficulty. A similar, but not so marked or regular, peristaltic constriction accompanies the formation of the second polar globule. In C. complanata the furrow often appears raised in the middle, giving it the appearance of being double. It is possible that the same phenomenon has been fixed by reagents in the Limax egg shown in Fig. 55. The fate of the germinative vesicle and the significance of the polar globules are discussed by Whitman at some length. The germinative vesicle is not totally eliminated, so there is really no enuclear or cytode stage, which, moreover, from a priort grounds could hardly be expected. “Ontogeny furnishes numerous examples of reversion, but I believe no case in which reversion is followed by progression to the same point — again.” Although the genetic connection of the archiamphiaster and the germinative vesicle were not absolutely demonstrated in Clepsine, yet, granting this,. “the proof in Clepsine is as complete as it well can be for opaque eggs that a part of the germinative vesicle persists as a nu- clear element ” (p. 34). The occurrence of polar globules the author thinks still a matter of doubt in birds, reptiles, amphibians, most fishes, tunicates, arthropods, and rotifers. I have shown it to be highly probable, however, that Stras- burger has seen stages initiatory to the formation of a polar globule in Phallusia. Whitman maintains that it is impossible to make a direct comparison of the elimination of the entire germinative vesicle, as represented by Balfour and Oellacher, with the formation of polar globules by amphias- tral division. The “pole-cells” in insects, as they form the basis of the sexual organs, cannot be equivalent to polar globules; nor can the so- called “testa-cells” of the ascidian egg. Perhaps the most interesting part of Whitman’s discussion is that which considers the historic origin of the polar globules (pp. 44—49), to which the reader must be referred, since there is space here for only 2 MUSEUM OF COMPARATIVE ZOOLOGY. 463 brief account. The objection to Biitschli’s theory, that the formation of polar globules is equivalent to the elimination of the “ nucleolus,” which occurs in many Infusoria as a result of (temporary ?) conjugation, is found in the fact that the polar globules are formed independently of fecunda- tion, while the “nucleolus” of Infusoria is ejected as a consequence of the conjugation. The view held by Biitschli, that the production of polar globules is a process by which the nucleus is rejuvenated, —a phenomenon, not. of the maturation of the egg, but of the earliest phase of its development, which may take place either parthenogenetically, or under the influence of fecundation, — and therefore that the meaning of this process is to be sought in the elimination of a part of the egg nucleus, is not, according to Whitman, the interpretation “most in harmony with the phenomena of conjugation, the characteristic feature of which is the addition rather than the removal of substance.” For this reason the forms both of total and of temporary conjugation observed among Infusoria are fundamen- tally the same, the latter being, so to speak, an abridgment of the former. “Tmpregnation in both plants and animals consists,” says Whitman, “in a complete and permanent fusion between corresponding parts of two unicellular individuals, fully analogous to what happens in the first mode of conjugation, with this difference, that polar globules and ‘canal ‘cells’ are produced before the fusion begins, or at least before it is com- pleted,” but not so in the case of conjugation. “In what relation, then, do polar globules stand to impregnation?” “That there is no necessary _ [eausal] connection is in harmony with the absence of such corpuscles in - conjugation.” A temporal relation, however, does exist. Whitman adopts the view which homologizes the “canal cells” of plants with the polar globules. In the former the “canal cells” stand at the end of a series of asexual generations, the impregnated ege beginning a new series that will end like the preceding. “Just as fecundation in plants is fol- lowed by cell proliferation culminating in sexually differentiated cells, : destined to copulate and renew the cycle of changes, — all other products of the proliferation (canal cells with the rest) eventually dying out, — so | in Infusoria conjugation is succeeded by reproduction by fission, the ulti- | mate products of which are sexually differentiated individuals. The | chief difference here is, that in one case (Infusoria) all (?), in the other } | only a comparatively few, individuals become capable of gamic repro- ; duction ; but this difference, having reference only to a specialization of , | function which necessarily accompanies the development of a multicellu- » lar organism, authorizes no fundamental distinction. In Metazoa, like- 464 BULLETIN OF THE wise, a gamic cell-generation is followed by a line of agamic generations, the last of which are the small cells called by Robin polar globules. With the production of these globules we arrive at the sexually ripe egg, In accordance with all this, I interpret the formation of polar globules as a relic of the primitive mode of asexual reproduction, which normally pre- cedes fecundation, and is therefore no part of the process of impregna- tion. This interpretation accounts for the otherwise inexplicable fact that amphiastral divisions of the nucleus introduce the formation of the directive cells, and is in harmony with the absence of such cells in Infu- soria, and their general occurrence among plants and animals.” The subject of ‘polar rings” is considered in connection with that of pronuclei, and both are reviewed farther on. (See p. 503.) The second of the papers by O. Hertwic ('78*) of which a synopsis was published in 1877 contains the results of studies. on ccelentrates, worms, echinoderms, and mollusks. Among the celentrates the uni- nucleolar is the prevailing but not the exclusive condition of the germi- native vesicle. As in Asteracanthion the nucleolus is composed of two substances of different refractive power. The eggs of Aiginopsis and Mitrocoma when excluded are naked and agree with Toxopneustes in the early formation and loss of the polar globules, which can be found only by the study of eggs taken from the ovary. In Pelagia and Nausithoé there are two or three polar globules, which are retained in contact with the yolk by the gelatinous mass in which the eggs are laid, and which contain one or several nucleolar structures. If three globules are formed, the third arises by a division of the one first formed. All the eggs which are ripe and excluded into the sea-water already possess before fertilization a small homogeneous egg nucleus at the surface of the yolk. Of the Siphonophore the eggs of both Physophora hydrostatica and Hippopodius gleba exhibited each two polar globules, mistaken by P. E. Miiller in the case of the latter genus for spermatozoa. Among the Ctenophore, Gegenbauria cordata exhibited constantly two — polar globules, at some little distance from an egg nucleus which lay at the boundary of the yolk granules and cortical layer of protoplasm. A third body like the polar globules was occasionally seen a little distance from the latter, but why he should suggest that it might be a sperma- tozoon rather than a third polar globule, I do not understand. The germinative vesicle of the immature eggs of Sagitta is peculiar in having, instead of a single large nucleolus, a number of smaller nucleoli which lie on the membrane of the vesicle. Also a reticular substance is MUSEUM OF COMPARATIVE ZOOLOGY. 465 visible in the interior of the vesicle. The latter at maturity approaches the surface of the yolk and is dissolved before the egg leaves the ovarium. In eggs treated with acetic acid the Richtungsspindel was observed to have a peculiar structure. It was composed of a bundle of stout, short, lustrous rods of -uniform thickness throughout, and so arranged as to appear in optical cross-section as a circle of conspicuous granules. The formation of two polar globules, and the subsequent appearance of an “eoo nucleus ” ‘(at first as a small vacuole in the periphery of the yolk under the polar globules), were observed in the living egg to follow each other after intervals of a quarter of an hour only. In already excluded egos of Alciope a maturation spindle of considerable size was observed. The germinative dot in eggs of Ascidia intestinalis, as well as in Physo- phora, in Spheerechinus, and in several mollusks (Unio, Tellina, Helix), was found to be really composed of two substances, having, as in the case of Asteracanthion, different physical and micro-chemical properties. To designate these Hertwig uses the name Juwclein, for the larger, less refringent, and usually enveloping substance ; and Paranuclein, for the smaller body. As the names imply, he considers the former as the essential part and the latter as the accessory part. This he does not- withstanding the fact, already established by his studies on Asteracan- thion, that the “ Paranuclein” (as I conclude from the account of its deportment in the two cases) is the part which is “7m erster Linie” engaged in the transmigratory changes accompanying the formation of the first maturation spindle. Flemming, moreover, holds, as Hertwig states, the reverse opinion as far as regards the case of lamellibranchs. Hertwig gives figures from his earlier studies on Heemopis which now have greater interest in view of his observations on the starfish. They represent stages in the formation of the ‘“ Richtungsspindel” when por- tions of the nuclear substance are still to be found in the vicinity of the spindle figure. These bodies entirely disappear with the completion of the spindle, i. e. by the time the polar globules begin to be formed. The formation of two polar globules in the sea-urchin (Spherechinus brevispinosus) takes place in nearly the same manner as in the star- fish, except that the two maturation spindles and archiamphiasters are larger. Hertwig acknowledges that his previous representations of the metamorphosis of the germinative vesicle were produced from eggs in a pathological condition. The reason why the maturation spindle was not previously found in mature eggs is explained by the polar globules being formed in the ovary, and at a time when the eggs do not pos- Sess a firm membrane, so that the latter are lost in the ovarial fluid. "OL. VI.—NO. 12. 30 466 BULLETIN OF THE The eggs of the sea-urchin are peculiar from the great length of time (sixteen to eighteen hours) during which they remain capable of normal fertilization. The abnormal penetration of several spermatozoa Hertwig thinks is due to the protoplasm, impaired in its vital energies, no longer offering resistance to such penetration. . Among mollusks the eggs of Mytilus afforded excellent results, which in the main so far corroborate the evidence of his other observations that I confine myself to a few minor points. Before the first maturation spindle has reached the surface of the yolk a corpuscle (sometimes divided into halves) is seen at some distance from the spindle. He is not quite certain, but inclines to the opinion that it consists of nuclear substance, for it disappears some time after fertilization, i.e. before the formation of the polar globules. It is interesting to observe that the ege does not advance beyond the formation of the first maturation spindle unless it is fertilized. Then, after fifteen minutes, the polar globules are quickly formed (the second follows the first after twenty-five minutes), and carry before them the double-contoured egg membrane. The spindle becomes shortened and thicker before the globule is formed. A promi- nence arises at the vegetative pole of the egg when the first cleavage amphiaster makes its appearance; it ultimately forms a part of the greater (vegetative) segmentation sphere. The criticism I have made on the account given by Fol of the early changes in pteropod eggs, simply from a comparison with the changes which occur in Limax, is strengthened by the conclusions to which Hertwig arrives from a study of mollusks more nearly related to those investigated by Fol. It follows from Hertwig’s -observations on Tiede- mannia Neapolitana and Cymbulia Peronii that the formation of polar globules and of the egg nucleus takes place in essentially the same manner as in Asteracanthion. The two polar globules are formed one after the other, — not by the division of a single globule. The “ Ver- dichtungszone” of the maturation spindle may in Tiedemannia be seen in the living egg as a row of short dark rods. He passes over the formation of the second maturation spindle by simply saying that the spindle-half which remains after the second polar globule is formed, completes itself again. The female pronucleus arises as a cluster of vacuoles. It is noticeable that in all the mollusks de- scribed by Hertwig, except lamellibranchs, it remains very near the animal pole of the egg just as in Limax, and that in all cases the female pronucleus, unlike Limax, seems to exercise less influence on the surrounding protoplasm than does the male pronncleus. a ieee o : MUSEUM OF COMPARATIVE ZOOLOGY. 467 The phenomena in Pterotrachea and Phyllirhoé are so nearly the same that they are described jointly, and afford excellent results on the nature of the metamorphosis. The spindle is formed within, and therefore out of the substance of, the germinative vesicle. On preparations made with acetic acid the spindle is found to lie through the middle of the vesicle (or a little eccentric), its ends with their extensive asters lying at two poles of the vesicle where its wall has been dissolved. The coagulated nuclear fluid (Kernsaft) is distinguishable after the membrane of the vesicle has been entirely dissolved. When the spindle has taken a radial position the yolk exhibits a depression at the point where one of its ends reaches the surface. The second spindle is much smaller than the first. While I can fully acquiesce in a majority of the points defended by Buancuarp (78, pp. 747-754), I cannot think all the conclusions he has reached are justified by the literature which he has so recently reviewed. It is at least confusing for him to say, “The germinative vesicle disap- pears, not because it is dissolved in, but because it is expelled from the vitellus, just as Pouchet maintained thirty years ago,” even though he subsequently gives a less prejudiced account of these changes. It is likewise very unsatisfactory, because incomplete, to say that the germi- native vesicle in escaping from the vitellus leaves behind in the yolk a part of its fluid (suc) in a state of solution. That I may not mis- represent the conclusions of Blanchard, I must add that he recognizes the derivation of the female pronucleus from the half of the second spindle which remains in the vitellus and “ se désorganise.” I do not understand how a process of disorganization can result directly in the construction of a new nucleus, and cannot share the belief that the spindle metamorphosis of the germinative vesicle is “a consequence of its natural death,” since thereby I should be compelled to look upon the spindle metamorphosis which accompanies every subsequent cell division — although presenting the most striking evidence of activity — as a consequence of the death of the nucleus! One should not maintain, as Blanchard does, that the polar globules exercise a considerable influ- ence on the direction of the segmentation furrows and the reciprocal relations of the blastomeres. It cannot be doubted that there exists a constant spatial relation between the polar globules and the furrows, but to seek the cause of this coincidence in a supposed influence of the polar globules over the position of the furrows is to adopt an explana- tion of which there has as yet been adduced no proof, and which is much less satisfactory than that which makes the position of the place both where the polar globules shall emerge and where segmentation shall 468 BULLETIN OF THE subsequently begin depend upon the same cause (not yet fully under- stood), a cause which effects the segregation of the more active con- stituents of the egg about the pole in question before ether of these phenomena have taken formal expression. Blanchard pertinently objects to Rabl’s theory of the protective office of the polar globules, on the ground that, if injurious pressure were exerted by the egg membrane, the globules would only serve to increase its damaging effect by concentrating the pressure upon a more limited extent of the embryo’s surface, and thereby necessarily increasing pro- portionally the intensity of the pressure. 3. Fecundation. It is my purpose to review such papers as treat the subject of fecun- dation in the light of the recent discoveries of nuclear copulation, or such as have paved the way to so fundamentally important a conception of the nature of the process in question. The order in which these phe- nomena have been discovered has been nearly the reverse of the succes-_ sion in which the events of fecundation make their appearance. It was in the earlier part of the present decade that a beginning was made in divesting the /ater stages of fecundation of some of their mysteries, and only by a sort of retrogressive exploration that we have within the past two or three years come to understand better the earlier stages of the process, and to put all in more satisfactory correlation. ~ Burscuur (737) was one of the earliest observers to trace some of the changes which overtake the pronuclei, but he could give no account of their origin, and therefore had no idea that they were intimately con- nected with the fecundation of the egg, as he also was in doubt about their actual coalescence. His account of the phenomena accompanying their union has been, for the sake of convenience, given in another connection (pp. 280, 396). The studies of Wert (73) I am only acquainted with through Hof- mann and Schwalbe’s ‘‘Jahresbericht,” etc., from which it is to be learned that he has observed in rabbit eggs taken from the oviduct between seventeen and forty-six hours after fecundation (should probably read “after copulation ”) living spermatozoa, in four cases within the egg protoplasm itself. Like Van Beneden, Weil also saw two nuclei (male and female pronuclei) before the beginning of segmentation. What has already been said of the origin of the female pronucleus, as described by Auerbach, is true of the male pronucleus. Concerning the further changes of the pronuclei after they meet in the centre of the MUSEUM OF COMPARATIVE ZOOLOGY. 469 egg, AumRBacH (’74, pp. 210-217) says that they continue their mo- tion until they become, to a considerable extent, mutually flattened. The line of contact is very fine, and the failure of the nuclei to melt together at once is due to that condition of the surface of the two nu- clear drops known to physicists as superficial tension, and not to the existence of a veritable nuclear membrane. ‘The flattened pair of nuclei soon commence a rotary motion around an axis perpendicular to the long axis of the egg, which continues till the plane of separation, which originally was perpendicular to the long axis, comes to lie parallel with it. The rotation, like the migration of the nuclei, is passive, i. e. is effected by the contractility of the protoplasm. Toward the end of this rotary motion the nuclei become more flattened, and the nucleoli be- come, one after the other, gradually paler and somewhat larger, and then suddenly their substance scatters, forming a cloud, which almost immediately vanishes. After this the line of separation suddenly dis- appears along its whole extent, and the two nuclei are one. If it were a layer of protoplasm or a membrane which separated the nuclei, it could not disappear throughout its entire length at the same instant. The single nucleus by elongation now assumes a rhombic or broad- spindle form. When he comes to an interpretation of the meaning of this melting together of two nuclear structures, Auerbach believes that it is to be un- derstood as a sort of conjugation (pp. 248, 249), — a necessary introduc- tion to the process of successive nuclear increase, which is soon to follow. Hence it is a kind of nuclear reproduction. Just as for the reproduction of individual organisms a copulation of two individuals is so often indis- pensable, so for unicellular organisms is that of two cells. Every conju- gation has manifestly for its end the improvement (by a process of intermingling) of individual peculiarities, —the mutual complementing of deficiencies. A difference in the two uniting elements, so common elsewhere, is not wanting here. ‘The difference in the place of origin of the polar nuclei —the one at the smaller pole where the spermatozoa penetrated, the other at the opposite pole — will influence the quality of the nuclear material and induce one-sided faults in the composition of each. To correct this is the object of the migration and confluence of the primitive nuclei. But if these were simply to meet and coalesce, then, owing to the inability of the thick nuclear fluids immediately to intermingle, the whole process would be futile, since with the first segmentation each half of the nuclear mass would be relegated to the half of the yolk in which it arose. This is obviated by the rotation of 470 BULLETIN OF THE the mass through 90°, whereby each half supplements the half of its own nuclear fluid by the half of that which arose at the opposite pole of the egg. In Cephalobus rigidus Butscuut ("75, p. 202) says he has seen the process of fecundation in the most satisfactory manner. As soon as the egg reaches the first spermatozodn of the seminal vesicle it unites with it at once. The spermatozoon attaches itself closely to the surface of the yolk, and when the latter has entered the uterus appears already fused with it. The egg certainly combines with no other spermatozodn in its passage through the seminal vesicle. In Cucullanus the egg at the moment of fecundation was not observed, but fecundated eggs dis- closed clearly the entered spermatozoén as a cluster of dark granules sur- rounded by a clear area. It is therefore not at once fused with the yolk in this case. The results reached in this preliminary account regarding the origin and fate of the pronuclei I have given in connection with the subject of maturation (p. 403). Biitschli fails to connect either of the pronuclei directly with the penetration of a spermatozodn, but attrib-_ utes the beginning of the maturation phenomena to the influence of fecundation. Since by the ejection of the polar globule a component of the nucleus is removed, it is readily to be inferred that the same is replaced by components of the spermatozodn, especially since subse- quently (during segmentation) a part (spindle) corresponding to the polar globules is found in the nucleus. There is ground for the state- ment that the essential thing in fecundation consists in the removal of the old nucleolus, and the formation of a new one to which elements of the spermatozodn contribute (p. 210). . For Bombinator GorttEe (75, pp. 51 et seg.) describes the disappear- ance of the germinative vesicle, which leaves behind for some time a starlike figure in the upper half of the yolk. Immediately after fecun- dation in the more advanced eggs, a “yolk nucleus ” (Dotterkern) has already made its appearance near the middle of the egg as a large, round, somewhat flattened body, with distinct but not sharp contour. The finely granular substance of the disintegrated germinative vesicle reaches within its territory, but with such want of uniformity as to justify the assumption that the two structures sustain only a chance relationship. This “Dotterkern” migrates toward the upper pole of the egg, while the discoloration of the yolk, due to the disintegration of the germinative vesicle, disappears entirely ; and thereupon is formed within it a delicate round corpuscle —the first “ Lebenskeim ” — which induces the further development of the egg. This “life germ” per- MUSEUM OF COMPARATIVE ZOOLOGY. A71 sists when, soon after, the yolk nucleus becomes faintly outlined and disappears. . As I have elsewhere indicated, it is probable that Fou (75%, Pl. VII. Fig. 2, and Pl. VIII. Fig. 2) saw and figured for Pteropoda, without com- prehending its true significance, the male pronucleus, both some time be- fore and also when it was about to join the female pronucleus, in the former case as the centre of a well-expressed aster. O. Hertwie (75, pp. 378-398, Taf. XI.) was the first to definitely connect one of the pronuclei (Spermakern) with a spermatozoon. In from five to ten minutes after artificial fertilization of the eggs of the sea-urchin there appears near the surface a small clear space from which the yolk granules have disappeared. This space increases a little in size, and at the same time the neighboring yolk granules assume a radial arrangement about it as a centre; at first limited to its immediate vicinity, but gradually becoming more extensive and more distinct. A small homogeneous body makes its appearance in this space, from which it only slightly differs in its refractive power. Sometimes a delicate line was seen stretching from this body to the periphery of the yolk, whence it continued into the perivitelline space as a fine thread. This radial figure migrates rapidly (requiring only about five minutes) from the periphery to near the centre of the egg; here the corpuscle encounters the “egg nucleus” (female pronucleus), which has meantime slowly approached the stellate figure. The egg nucleus has a diameter of 13; the corpuscle, of 44. The nucleus now undergoes a slight ameboid change of form, both structures become less distinct, and the smaller finally disappears. A little later the limitation of the egg nucleus again becomes distinct, but the smaller body is not to be seen. The nucleus is larger than before, and of spherical form. Meanwhile the stellate figure, in which the egg nucleus has now come to lie, has increased in extent till its rays reach nearly to the periphery of the yolk on all sides. The use of osmic acid and Beale’s carmine confirms the results of these observations on living eggs. The stellate figure is, however, less conspic- uous than in the fresh condition. By this treatment it is found that both the egg nucleus and the central corpuscle of the stellate figure be- come deeply stained. This warrants the conclusion that both consist of nuclear substance. The corpuscle is a little more intensely colored than the egg nucleus, a condition to be accounted for by the more compact condition of its substance. Furthermore, stages in which the two nuclear structures are in contact, and later such as show only a single nuclear 472 BULLETIN OF THE structure, justify the opinion that the single nucleus found in the egg emmediately before segmentation, and surrounded by rays of yolk granules, as the result of the copulation of two nuclei. Hertwig also reports that, while in most cases only one clear spot makes its appearance in the pe- riphery of the yolk, occasionally more (up to four) have been observed to make their way to the egg nucleus ; but after the appearance of anoma- lous nuclear figures, the eggs soon perished. It is therefore probable that these eggs were from the beginning pathologically altered. In the interpretation of these observations he concludes that the con- stancy of their appearance at a uniform interval after the mingling of the sexual elements is evidence that they are dependent on fertilization. From this and the observed filament it is not to be doubted that these changes are referable to the penetration into the yolk of a sperma- tozoon, of which the tail is the observed filament, while the head (its nucleus) becomes the ‘‘Spermakern.” The tail is probably dissolved either at once or during the migration of the sperm nucleus. The homogeneous protoplasmic area and the radial figure are apparently induced by the sperm nucleus which occupies their centre, in the fol- lowing way: the nucleus exerts an attractive influence on the homoge- neous components of the yolk, which thus become most densely collected around the nucleus, and thence radiate in all directions. The yolk gran- ules passively assume a position in the interstices between the rays of the attracted substance. The most important part of fecundation, hitherto explained as the copulation of two cells,* is found in the fusion of the two nuclei from which “arises first a nucleus (nucleus of the first cleavage-sphere) equipped with living forces, which effectively stimulates, and in many respects controls, the further process of development in the yolk.” In a foot-note (p. 386) Hertwig calls attention to the fact that for the time being the egg cell may be considered as in an hermaphroditie condi- tion, inasmuch as two sexually different nuclei are present in a common protoplasmic mass. Further, since the “nucleus” and the “nucleolus ” of Infusoria are, from the changes they undergo in reproduction, com- parable with the egg nucleus and sperm nucleus respectively, it follows that the Infusoria may be considered as hermaphroditie unicellular organ- isms, inasmuch as the sexual differentiation of the nuclear substance, which has been accomplished in other organisms in two separate cells, is with them effected in a single cell. In a foot-note Burscati (75%, p. 109) says his recent studies tend to * See Haeckel "74, pp. 135-138, and "75, pp. 482, 483. MUSEUM OF COMPARATIVE ZOOLOGY. 473 confirm his opinion that the essence of fecundation consists in a total or * partial renewal of the nucleus of the egg cell. Hensen (75, p. 238, Taf. VIII. Figs. 5-8) never saw ‘ein Samen- fidchen in den Dotter hinein kriechen,” but has often seen these cor- puscles imbedded, either entirely or the head only, in the yolk in the case of the guinea-pig and the rabbit, and draws the general conclusion (p. 241) that in the case of these animals more than one spermatozoon can penetrate the yolk, where, under definite formal changes of the head, it is dissolved, and that in this manner the fecundation of the egg is accomplished. Ep. vaN Benepen (75, pp. 693-695) was never able to observe the penetration of a spermatozoon into the vitellus of the rabbit’s egg ; but from often finding spermatozoa very closely adherent to the surface of the yolk, he ventures to express the belief that ‘“ fecundation consists essentially in the fusion of the spermatic substance with the superficial layer of the vitelline globe.” His account of the formation and union of the pronuclei is given on pages 412 to 414. The penetration of spermatozoa into the egg, which Rosin maintains (75, p. 21), does not imply a penetration into the yolk substance. The ultimate molecular union of the substance of a large number of those which penetrate the membrane and are liquefied, is evidently only an inference from a supposed diminution of those still found in the peri- vitelline fluid at later stages (see Robin ’62, p. 87). ‘The retraction of the yolk, the changes which supervene in its granules, the formation of polar globules, are partial phenomena which occur with eggs whether fecundated or not ; but the production of the witelline nucleus only takes place in ovules into which spermatozoa have penetrated, i. e. [in ovules] to the vitellus of which male substance has been united.” (75, p. 86.) Notwithstanding the accuracy of the greater part of this statement, it does not follow that the author understood the true origin of the nucleus of the first segmentation sphere,— his ‘“‘noyau vitellin.” In fact, it has in his opinion an origin entirely independent of the germinative vesicle, at the centre of the yolk, by a molecular association of “ principes immé- diats” of the vitellus. It is with the appearance of this nucleus that the ovule takes on the characters of a new being, and ceases to be an anatomical element of the adult animal which produces it. Thus, of all the parts which compose the ovule before maturity, the vitellus, he believes, is the only one which serves for the production of a new being. I shall not reproduce the second part of Van Benepen’s (’76%, pp. 76 - 474. BULLETIN OF THE 83, and ’76°, pp. 178-182) paper * on the germinal vesicle and the first embryonic nucleus, for it is an attempt to harmonize Hertwig’s observa- tions on Toxopneustes with the author’s own studies on mammals, which was only made possible, as Hertwig (77, p. 77) himself has very clearly shown, by a misconception of the account given by the latter. Van Beneden’s assumption that Hertwig’s ‘“‘Spermakern” is a nucleolus finds no support in Hertwig’s description, and the protoplasmic area surround- ing it is certainly not a nucleus, and therefore not comparable with Van Beneden’s “pronucleus périphérique.” While there is no reason to question the interpretation which Van Beneden assigns to his own ob- servations, his attempts to subject Hertwig’s observations to an unnatu- ral alliance with his own must be regarded as unsuccessful. In the egg of the common toad after fertilization Van BamBexe (76, pp. 117-135, Pl. II.) has observed that meridional sections exhibit, in- stead of a single pigmented trail, —the claviform body of the unfertil- ized ege, —two such trails. One of these, the “trainée en boudin,” is slightly swollen at its internal end, and reaches nearer to the centre of the yolk than the second, — “trainée triangulaire,” — about the inner end of which it is curved as about a centre. At its periphery it abuts upon the germinative fossa. This the author thinks is unquestionably the claviform figure of the unfertilized egg made to take a curved course by the pushing in against it of the second or triangular trail. The latter is also mingled at its base with the pigmented cortical layer of the supe- rior half of the egg; its apex is directed inward, and is slightly curved upward so as to terminate in the space surrounded by the curved “ trainée en boudin.” In the terminal part of the triangular trail was once seen a clear homogeneous point limited by a strongly pigmented contour, which the author considers the nucleus of the first segmentation sphere. Similar conditions are found in fertilized eggs of Pelobates. Here, however, the claviform figure is not curved, and its inferior enlargement, in place of being a pigmented mass, is less deeply colored than the zone which immediately surrounds it. The apex of the triangular trail, hay- ing come to occupy the centre of this enlargement, is seen to abut upon an elliptical nuclear mass (nucleus of first segmentation sphere), which is a little clearer than the surrounding yolk, and is limited by a pig- mented contour, whence granular striations of the yolk radiate. Observations of a similar kind on the eggs of the Axolotl convince the * The English translation of this paper ("76°) exhibits an omission which is of rather vital importance to Van Beneden’s argument. It may be corrected by insert- ing, in the 15th line from the top of p. 181, “‘ nuclei of the” before ‘ cleavage spheres. ” | | | ) | MUSEUM OF COMPARATIVE ZOOLOGY. 475 author that the triangular trail of the tailless Batrachia is homologous with that which takes its origin from the “ trous vitellins,” as previously described by him (’70, pp. 64, 65). Finally, after a review of the liter- ature, Van Bambeke arrives at the conclusion that the eggs of the Batrachia, immediately after impregnation, still embrace traces of the claviform figure, but nothing discloses the presence of the ‘“ EKikern” of Hertwig, or the “ pronucleus central” of Van Beneden. The nucleus of the first segmentation sphere arises from the periphery ; it very probably results from the penetration into the vitellus of a spermatozoon, which leaves as a trace of its passage the “trou vitellins” and the “trainée pigmentaire.” In Nephelis, after the conversion of the germinative vesicle into a nuclear spindle, Burscuti (76, pp. 216, 217) has seen a little elevation of clear protoplasm near the animal pole of the yolk, and believes it is caused by the union of a spermatozoon. with the yolk, during which the spermatozoon, possibly by swelling, has become metamorphosed into the protuberance. Other phenomena, which Biitschli did not think of connecting with fecundation, are probably phases of that process. The “third” system of rays about a homogeneous area we may now safely infer to be the male aster. The relation which the nucleus (male pronucleus) sustains to this ‘‘area” deserves attention. According to the text, “it always lies nearly in the periphery of the central area.” From Fig. 3, Taf. L, it is evident that it lies in that part of the periphery nearest the female pro- nucleus. I do not know of any other observation which agrees with this in the particular last mentioned. In eggs of Cucullanus that have passed the seminal receptacle (p. 223), a clear corpuscle, which en- closes a cluster of granules, is found imbedded in the surface of the yolk. ‘ It is, says the author, the result of the union of a spermatozoén with the yolk (see Taf. III. Figs. 1, 7, 12). It, however, disappears before the beginning of the formation of new nuclei. The latter arise close under the surface of the yolk, and are from the beginning distinctly vesicular, with dark envelope and granular contents, but never acquire a special nucleolus. They migrate toward the centre and become fused into a single nucleus. In Anguillula rigida (pp. 232, 233) the egg unites with the first spermatozodn with which it comes in contact, but never with a second. In the mollusks studied (p. 238) the first evidence of the existence of a male aster was observed (Lymnzus) when the first polar. globule had been eliminated. It already occupied the centre of the yolk. A nucleus 476 BULLETIN OF THE (male pronucleus) was not observed in connection with this aster. From among the large number of nuclear structures (nine in Lymnzeus) that ap- — pear in the yolk under the place of the polar globules in Biitschli’s figures, it is not possible to say always which represents the male pronucleus, though there is usually one (Taf. IV. Figs. 7-9) which from its deeper position or larger size may perhaps be inferred to be such. In Succinea the pronuclei closely resemble those which I have found in Limax, the membrane (?) being much wrinkled by the action of acetic acid. In Fig. 23 of Biitschli’s Taf. IV. the nuclei occupy a peculiar po- sition, their plane of contact lying in the animal radius of the yolk. I have never seen just such a relation. Whether in Succinea the male pronucleus is at any time surrounded with a radiate structure of the yolk, does not appear from Biitschli’s studies. I am inclined to think it may be wanting, as in Limax. In view of the possible absence of stellate figures in these cases, it still remains with me, as it was with Biitschli, an open question, whether the central stellate figure of his Fig. 4 is really a newly formed aster. Against the probability of its having any- thing to do with the male pronucleus, it may be urged, in addition to the probable absence of a male aster, that no nuclear (vacuolar) structure was observed in its immediate vicinity, and that the aster occupies the centre of the yolk at so early a stage. Biitschli evidently inclines to the opinion that it has no genetic connection with the first spindle. If he | is right, then it must be regarded as the male aster; but I am inclined to believe, for the reasons just given, that it is the deeper star of the second archiamphiaster, whose spindle has not been distinguished. Biitschli endeavors (p. 391) to connect the “ Neubildung” of nuclei in the first segmentation sphere with the segregation of very clear nearly homogeneous protoplasm. It is usually collected at the place where the polar globules emerge, but it may be more widely distributed over the surface, and may even (Nephelis) collect at a point within the yolk. This clear protoplasm forms the centre of a system of rays, and within it the new nuclei arise from very minute beginnings. These beginnings are small compact corpuscles (p. 408) which rapidly become differentiated into small vesicles. Just as in the formation of the nuclei in cell divis- ion, so here the simplest primitive form is farthest from Auerbach’s con- ception, —an excavation in the protoplasm filled with a fluid, —it isa homogeneous, compact condition. Since each of the several nuclei pos- sesses the same histological structure as the nucleus which results from their fusion, there is no ground for uniting with Selenka in calling the former “nuclear germs,” nor for saying, with Strasburger, that they are MUSEUM OF COMPARATIVE ZOOLOGY. 477 not so many individual nuclei, but that they furnish the material for the construction of a nucleus. A comparison with the conjugation of Infusoria leads Biitschli to the conviction that in the fecundation of the egg similar modifications — “total or partial renewal of the nucleus, or a material revival of the same by the importation of a new part” — may be encountered (p. 438). The two nuclei (pronuclei) are alike, and arise in the same manner. There is ndt the least justification for interpreting them as egg nucleus and sperm nucleus in O. Hertwig’s sense. The existence of a multiple of nuclei is a phenomenon induced by the antecedent subdivision of the nucleus of a spermatozodn which penetrated the yolk, not by the pene- tration of several spermatozoa, as O. Hertwig concludes. To ascertain whether the formation of polar globules is dependent on fecundation the author instituted experiments on two nematodes (Rhab- ditis teres and R. pellio) rearing MUSEUM OF COMPARATIVE ZOOLOGY. safe b As was to have been expected, the events of maturation in Heteropoda show a greater resemblance to those in Limax than either of the other groups. The author withholds judgment as to whether the limiting layer of the ovule is in this instance a true membrane, since he has not satisfied himself experi- mentally of its physical and chemical properties. In young ovules it has the aspect of a membrane, but its internal contour becomes less distinct in those that are mature. Whether it is resorbed or mingled anew with the vitelline sarcode, it does not exist after the exclusion of the egg. The nucleus of the egg at the time of deposit is identical with the nucleus of the ovule (i.e. ger- minative vesicle). It then appears in the living egg as a clear spot at the centre of the yolk, which soon vanishes, and the central part of the vitellus then assumes a more homogeneous aspect, in which, however, a radial figure is discernible. In about half an hour there appears on one side of the yolk a clear space resting with a broad base at the surface, and continuing toward the centre in the form of a cone. It is composed of protoplasm without any “protolecith.” As it increases in size, the lecithic globules, especially near the surface, take on a radial arrangement about the centre of the clear space. In an hour and a half the protuberance of thé first polar globule appears, and within it one can distinguish the bipolar filaments and their enlargements without the use of reagents. Two hours and three quarters after exclusion the first globule is entirely detached, and the radial arrangement of the “lecith” indicates the formation of the second amphiaster; at this moment there appears a voluminous protuberance at the nutritive pole, composed of protolecith and sarcode. The superficial layer of the latter is here thicker than over the other parts of the yolk. At the end of three and a half hours the second giobule is fully detached, and the vitelline protuberance has mean- time entirely disappeared. Prolongations often seen arising from the surface of this protuberance (Pl. VIII. Fig. 9) are trabecule resulting from the retrac- tion of the albumen of the coagulated egg, and therefore do not pertain to the vitellus.* Fol is unable to give any explanation of the meaning of this pro- tuberance. — The metamorphosis of the germinative vesicle as shown by hard- ened eggs confirms in many ways the views at which I had arrived. The vesicle at the time of exclusion is still quite distinct, provided with a limiting layer, and embraces a network of sarcodic filaments, but contains only a few irregular refringent granules in place of a nucleolus. The enveloping layer, the so-called membrane of the vesicle, becomes less distinct, although it still remains visible. The vesicle diminishes a little in volume, but preserves an almost spherical form, without shrivelling. At the opposite poles of this great rounded cavity one now distinguishes two masses of granular substance, * It should be remarked in this connection, however, that the author subsequently (page 112) alludes to this as a protuberance ‘‘ with its accumulation of protoplasm and sometimes pseudopods at its surface (Pl. VIII. Fig. 9, Ev').” Since this is the same figure as that cited in connection with the description given above, it would appear that the author may have changed his opinion concerning these pointed ele- vations between the times of the two writings. 572 BULLETIN OF THE in texture exactly like that which surrounds the vesicle and stretches out between the globules of “protolecith.” “ These masses protrude slightly into the cavity of the germinative vesicle, which otherwise remains perfectly rounded.” * This internal limitation is therefore very easy to distinguish, but externally they are absolutely indistinguishable from the vitelline sarcode of which they form apart. From these masses stria soon arise which take the direction of me- ridional lines. These become more distinct, and are changed into [?] veritable filaments. Falling short of the equatorial plane, they do not yet encounter each other. During all the phases of their formation, the peripheral extremities of these filaments are in continurty with the protoplasmic network which occupies the interior of the nucleus. As the rays advance, the network disappears. It is more than probable that the rays are only a modification of the form of the intranuclear network, and that they result from a regular arrangement of its trabecule. This view of the origin of the spindle fibres is not directly reconcilable with the one I have expressed; nevertheless, I see no occasion to modify the argument based on the great distance which in Limax inter- venes between the nucleus and the centres of the asters. The account of the origin of the polar masses I will give in the words of the author. “ Quant aux amas polaires, leur origine premiere est bien plus difficile a établir. J’avoue que, pour ma part, je n’y suis pas parvenu et qu’a cet égard je ne puis que poser une alternative sans la résoudre. Ces amas peuvent provenir du sarcode intranucléaire qui se porterait aux deux pdles opposés du noyau et se confondrait avec le protoplasme vitellin, ou bien ils peuvent provenir du proto- plasme périnucléaire qui ferait irruption dans la cavité de la vésicule ; 4 moins encore que ces deux processus ne se produisent simultanément, et qu'il n’y ait, dés le premier instant, une fusion entre ces deux substances. Que cette fusion soit immédiate ou non, il est incontestable que les protoplasmes intra- et péri- nucléaire ne tardent pas 4 se confondre aux deux pdles, en sorte que, un peu plus t6t, un peu plus tard, il y a toujours fusion. “Tes amas polaires faisaient d’abord une légere saillie dans l’intérieur de la vésicule sphérique. Pendant la croissance des rayons intranucléaires, ils s’éloi- gnent du centre et font de part et d’autre hernie dans le vitellus. Il en résulte que la vésicule passe de la forme sphérique @ celle dun citron trés-court. Pen- dant ce temps les rayons nucléaires, qui se trouvent pres de Paxe qui rejoint les deux pdles, sont arrivés & se rencontrer et se sont sondés de manieére a consti- tuer quelques filaments bipolaires; les rayons latéraux de chaque aster vont encore se perdre dans le réseau intranucléaire.” ) The extranuclear rays arise at the same time as the intranuclear, and the growth of both is exactly alike. There is therefore a time during which each centre of attraction is surrounded by a system of rays without being yet joined to that of the neighboring aster. The amphiaster occupies at first an eccen- tric position. The small grains representing the nucleolus may possibly go directly to the spindle, since granules of entirely similar appearance are seen along the intranuclear rays when the amphiaster is still incomplete. The * Not italicized in the original. MUSEUM OF COMPARATIVE ZOOLOGY. 573 author, however, doubts the genetic connection, since these granules are often entirely wanting. Subsequently the amphiaster is completed by the welding of the intranuclear rays end to end, and the “granules de Bitschli” make their appearance as enlargements of the bipolar filaments. But the relation of these enlargements to the grains presented by the still isolated rays remained obscure. The amphiaster elongates, and at the same time stretches the mem- brane of the vesicle. The vitelline rays have increased in extent, and the centre of each aster is occupied by a few granulations, around which is a space occupied by homogeneous protoplasm. Meanwhile the membrane of the ger- minative vesicle assumes indefinite contours and entirely disappears. The amphiaster moves toward the periphery; at first oblique, it becomes perpen- dicular to the surface, with which the centre of one of the asters becomes almost “flush.” Then the surface is raised into a dome, and the enlarge- ments of the bipolar rays divide ; the first polar globule, composed of half the “amphiaster de rebut,” is detached. The internal half undergoes the same modifications as in Asterias, but the second amphiaster is smaller than the first. Portions of the bipolar filaments and their enlargements are readily dis- tinguished at, and some time after, the formation of the globule. The enlarge- ments all lie at the same height ; at the time of segmentation the polar globule has assumed the appearance of a cell with a large nucleus, and one or several nucleoli. They decompose, and have no part in the development of the egg. The views of the author, it will be observed, seem to have been modified in some particulars since the publication of his earlier paper on Heteropoda. See pp- 429, 430. The principal events of fecundation as described for Asterias have already (pp. 480, 486) been given. It is necessary to add only a few particulars. The “ cone of attraction” may extend to half the thickness of the mucilaginous layer if the spermatozoon advances slowly, but is much shorter and more rounded when it approaches quickly, for as soon as the contact between the two is effected, the cone commences to retract. Most spermatozoa enter the nutritive hemisphere, but one often sees a penetration in the formative half, even up to the immediate vicinity of the polar globules. At the moment when a space appears under the vitelline membrane around the point of fecundation, the differentiation, but not the elevation, of the membrane has extended quite around the vitellus. From this instant the egg is inaccessible to every sper- matozoon which reaches the membrane; for the vitellus is no longer able to produce a “céne d’attraction,” and in Asterias a spermatozodn is hardly capable of penetrating without the aid of this excrescence. The space embraced between the elevated membrane and the yolk is occupied by a transparent sub- stance, which cannot be a liquid, but must be a very clear jelly, since, if it were a liquid, the vitellus would change position, and the space could not remain of uniform thickness all around. Does this substance arise exclusively as a secre- tion from the yolk, or is there at the same time an imbibition through the vitelline membrane? If the former, the vitellus should suffer a diminution ot volume. It is difficult to determine whether this is so, on account of the 574 BULLETIN OF THE changes in the form of the yolk. If the latter diminishes in volume, it can be but little. The vitellus and membrane have a greater diameter than existed before the formation of the membrane. The author therefore speaks of an elevation of the latter, and not of a retraction, which appears to him doubtful. The orifice through the membrane at the “crater” which gave exit to the “cone of attraction,” and possibly existed during the early stages of the forma- tion of the “cone of exudation,” is no longer to be found after the complete dispersion of the latter cone, nor is the crater longer visible. Directly under- neath this “crater” of the membrane there is a corresponding but smaller depression in the surface of the yolk. This is still visible when the membrane is wholly elevated, but before the male pronucleus is formed. The latter appears as a small clear spot without granules immediately under the vitelline crater. The phenomena occurring in the sea-urchin have been considered at page 490. The vitelline membrane is elevated with greater rapidity and energy than in the case of Asterias. The zodsperm suffers little change of form at penetra- tion. It enters progressively by the action of the vitelline sarcode, and is not impelled by its cue, which has ceased its undulatory movements. The “cone of exudation” is extremely pale and very mobile. The author does not know whether this is a phenomenon of amceboid contractions or a continuous erup- tion of an almost liquid substance. The body of the spermatozodn once plunged into the yolk is often visible without the aid of reagents. The point of penetration is only determinable by the fact that the female pronucleus retires only part way from the formative pole toward the centre of the yolk. With this as a criterion it may be shown that the penetration takes place at any point, but perhaps more often in the nutritive hemisphere. The growth and union of the pronuclei is nearly the same in starfish and sea-urchin. In Asterias the clear spot where the zodsperm penetrated becomes the point of departure for the male pronucleus, which at first remains for sev- eral minutes immovable and without apparent change. The vitelline rays are all directed toward the centre of the spot ; some of them are slightly curved so as to abut at the point of the surface where the cone of exudation still per- sists. The rays become longer and more accentuated with the advance of the aster into the yolk. Its direction, at first centripetal, changes when the female pronucleus does not occupy the centre of the egg, so as to encounter the lat- ter. If the egg is fecundated before the completion of the polar globules, the male pronucleus remains at. the edge of the yolk in the condition of a small, hardly visible spot until they are eliminated. Both pronuclei then arise simul- taneously. In this case they meet between the centre and the formative pole, because the male pronucleus advances more rapidly. In the sea-urchin, while the clear spot is contiguous to the surface, its in- terior often shows a rounded refringent globule, which appears to correspond to the body of the spermatozo6n modified in form, and soon becomes in the living egg invisible. Treatment with osmic acid and carmine shows that the zoosperm preserves a few instants its conical form, then becomes rounded into MUSEUM OF COMPARATIVE ZOOLOGY. 575 a strongly colored corpuscle, which is surrounded by a clear area and rays. In approaching the female pronucleus, the corpuscle increases to nearly double its original size. Preparations made when the female pronucleus is already surrounded by rays of the male aster show that the nucleus is almost con- stantly oval, and drawn to a point on the side nearest the male pronucleus. The nature of the male pronucleus is especially elucidated in the star-fish. It is sometimes only as large as that of the sea-urchin, but at other times twice as large; in the latter case it no longer has a homogeneous appear- ance, but is surrounded by an enveloping layer which is darker than the contents. The cause of this difference is unknown, but it establishes a transi- tion between the condition shown by the sea-urchin and that of the Hetero- poda where the two pronuclei have the same size and texture. Were it not for this transition, it would be difficult to ascertain whether the dark cor- puscle of the sea-urchin corresponds to the pronucleus of the Heteropoda or only to its nucleolus. Besides the results already (p. 479) mentioned, the study of the pronu- clei in Sagitta have afforded other points of particular interest. The altered form, which I ventured to assume for the male pronucleus, is actually encoun- tered, and corresponds almost exactly with that of the pronuclei in Limax, Fig. 68. I extract the following from the author’s description of the changes. Although fecundated at the moment of deposit, the vitellus shows a male aster only at the time when the polar globules are formed. It probably exists already at the edge of the yolk, but it must be quite small, since it escapes observation. Soon after the elimination of the globules there appears near the surface of the yolk, usually at the nutritive pole, a round or oval vacuole, the male pronucleus. The female pronucleus appears almost at the same in- stant. They move toward the centre, increasing in size, and meet between it and the formative pole. The female pronucleus is without an aster, that of the male grows rapidly, and lies in advance of the pronucleus. The cavity of the male vacuole 1s surrounded by a sharp margin, except at the place where it touches the centre of the aster. There it appears open, as though the contents of the cavity passed by gradations into the substance forming the central mass of the aster. The vacuole always asswmes the form of a melon-seed. This description corre- sponds in almost every particular with the condition in Limax alluded to above. The author, believing from the appearance that the pronucleus is drawn on in a passive condition, and that the agency must be sought in the male aster, endeavored to show by reagents the presence of the body of a zoésperm, or a compact corpuscle, in the centre of the aster. Failing in this, “he must con- sider the vacuole and the central mass of the aster taken together as the homo- logue of the male pronucleus of other animals.” This conclusion, if extended to the cited case in Limax, would involve one in the necessity of identifying the central area of the same aster with both male and female pronucleus ; and in Sagitta certain stages in the approximation of the pronuclei (op. cit., Taf. X. Fig. 7) appear to present the same difficulty, for the relation of the female pronucleus to the aster is at this stage essentially the same as that of the male 576 BULLETIN OF THE pronucleus. In Sagitta both are “open” on the side toward the centre of the aster, and in Limax both are drawn out in the same manner, and their out- lines become less conspicuous on the side toward tne aster. But while Fol represents the line which indicates the contour of the pronucleus in Sagitta as terminating rather abruptly, I have simply seen the outline become very gradually less distinct, but never wholly interrupted. The pronuclei in Limax present the same smooth, even contour on the side toward the aster as else- where ; it is only less conspicuous, not less precise, on that side.* There is, besides, this difference in the two cases : in Sagitta the aster arises in connec- tion with the male pronucleus, but in Limax in connection with the female. At this stage (Pl. X. Fig. 7), continues the author, a eorpuscle is generally seen suspended in the liquid of the cavity of each of the vacuoles, near the side with which they are about to come in contact. They are very dis- tinct, owing to the low refractive power of the liquid, and are comparable to the nucleoli found in the pronuclei of other animals. The pronuclei have the form of a grape from which the stem has been torn; it is by this trun- eate side that they approach each other, separated by only a thin layer of vitelline substance. Some of the rays of the aster now converge toward the space which separates the two pronuclei, and the others toward the infe- rior t extremity of the male pronucleus. When the pronuclei meet, the rays extend around both, converging toward the line which separates them. In coupling, they are mutually flattened. Fol’s Fig. 10 seems to indicate that they are no longer “ open” when this flattening begins. They always deport themselves optically, he continues, like vacuoles full of liquid in the midst of a denser substance.- The contours are perfectly distinct, but simple and without indication of a membrane or limiting layer. Variable sarcodic masses are visible within the pronuclei. The rounded mass (nucleolus) of the pre- ceding stage has disappeared, and in its place are seen sometimes filaments, sometimes partitions, at other times streaks of sarcode stretching across the cavity in various directions, and exhibiting enlargements of all forms and sizes. The stars of the first cleavage amphiaster evidently arise in Sagitta, also, he- fore the fusion of the pronuclei ; for the author says that, when considerably flattened, there often appear at their opposite lateral edges small lenticular masses which project into their cavity. (Compare loc. cit., Taf. X. Fig. 9.) The corresponding events in the Heteropoda offer many points of resem- blance with Limax. In one place the author speaks incidentally of the mul- tiple condition of the female pronucleus. When it is composed of two or three small nuclei, each of them, he says, contains its own nucleolus. The figure * From the difficulty of rendering a sharp outline on stone with the crayon, the pointed ends of the pronuclei in Fig. 68 are not quite so definite, especially in the later prints, as they should be. + From the figures cited it is evident that the blunt ae of the pronucleus is meant, although it is wpypermost in the figure. The description may date from a period before the author began to deviate from the customary method, by placing the vegetative pole of his figures uppermost. MUSEUM OF COMPARATIVE ZOOLOGY. 577 cited (PI. I. Fig. 13) is the only one which shows such a condition, and even in this one of the small nuclei is so covered by the other that the proof of their independence is not conveyed by the figure alone. If this condition really is met with, it must be very rare, for the author would otherwise have given a more detailed account of it. The internal star of the second amphiaster is much less developed and disappears earlier than in Limax. At its first appearance the male pronucleus is situated just underneath the surface of the yolk, rarely in the immediate vicinity of the nutritive pole. though more often in the nutritive hemisphere. It has no relation with the protuberance at the nutritive pole. He believes the latter is more accentuated when this pronucleus arises in the formative hemisphere. Both pronuclei develop with the same rapidity and in the same manner; each soon presents a large nucleolus in its interior; but the female pronucleus advances little or not at all toward the centre of the vitellus, because [?] it is soon joined by the male pronucleus, whose motion is infinitely more rapid. After treatment with picric or acetic acid the pronuclei are, at the moment of their appearance, homogeneous. A little later a certain number of small spherical grains, each of which is furnished with a black point in its centre, appear in the interior. Still later the pronuclei present the vesicular character of true nuclei, the limit being formed by an irregular layer of vari- able thickness. Neither osmic acid nor alcohol causes this layer to appear. The contents remain clear and transparent after treatment with osmic acid, but become granular with the other reagents mentioned. The nucleolus is variable in different eggs. More often there is only a large one in each nucleus, but it often happens that there are insted several small nucleoli. Since the latter condition occurs in less advanced stages, it may be that the nucleoli become fused, or that one is developed to the exclusion of the others. The rays which surround the male pronucleus during its displacement, and are visible in the living egg, disappear after the use of reagents. It is possible that the same may be the case with Limax. Fol has given no figures of this stellate arrange- ment, but his statement is explicit. The two pronuclei may have attained their full size at the time of contact, or “they may be still relatively little de- veloped (Fig. 7), and in the latter case the conjugated nucleus will be obliged to increase after its formation.” I doubt if this last statement is warranted by the figure cited. There does not appear to be here, more than with Limax, a veri- table conjugation nucleus. Unless I misinterpret this figure, it shows already the beginnings of the amphiaster of segmentation, and there cannot well be a further growth, but only a metamorphosis of the two pronuclei into a segmen- tation spindle. The nucleoli, continues Fol, still exist when the pronuclei are in juxtaposition, but they disappear at the moment when the latter are fused. During this fusion picric acid still causes the enveloping layer to appear, and, within, granulations arranged in lines diverging from the point of union. The results of the fecundation of immature or over-ripe eggs of Asterias, or such as are taken from animals kept in confinement, all being abnormal, have been given at pp. 484, 485, 491. The phenomena of segmentation were most extensively pursued in Toxo- VOL. VI. — NO. 12. 37 578 BULLETIN OF THE pneustes. After fecundation the vitellus remains in repose for about twenty minutes. There is a collection of transparent substance which forms an irregu- lar layer around the central nucleus. The radiations in the yolk appear before the nucleus has suffered reduction of volume; they are optically like the sub- stance which surrounds the nucleus, not like that of the nucleus itself. They diminish in breadth at the moment the latter is converted into an amphiaster. Auerbach’s theory is refuted by these facts. Subsequently the nucleus is a little elongated, and the perinuclear protoplasm takes the form of a disk sur- rounding the nucleus, as the ring of Saturn does its planet. The disk is oval; when seen in profile the vitelline rays appear to diverge from it like the barbs of a feather. Treated with acetic or picric acid, the radial structure, contrary to the effect produced in subsequent stages, becomes less distinct. This phase lasts about twenty minutes. The protoplasmic disk meantime gradually dimin- ishes in breadth and increases in length. Then it promptly becomes limited to two masses quite distinct from each other. The rays are no longer arranged like barbs, but like the spokes of a wheel. The nucleus becomes indistinct; reagents cause it to reappear in the form of a lemon. At the pointed extrem- ities the limiting layer of the nucleus projects outward, and serves as centres for the two systems of rays. In acetic acid the latter are seen with great distinct- ness ; they are without enlargements, and are soon lost in the midst of vitelline substance of uniform appearance. One or two of the granules in the nucleus are distinguished by their size and greater refringency, — perhaps a nucleolus in process of dissolution. Osmic acid confirms the existence of these conditions. Transitions from this to the next described phase are not often met with in the sea-urchin, but are more readily found in the heteropods, in connection with which they are described. In this next phase the spindle with equatorial fibre thickenings is already formed. It is during this stage that the second vitelline membrane begins to be detached. After treatment with picric acid there is no trace of an envelop- ing layer (membrane) around the nucleus; each aster is composed of distinct parts: a central, nearly spherical, clear, protoplasmic mass ; a peripheral gran- ular part, dark especially in the vicinity of the central mass, and of a radial texture remarkable for its delicacy and regularity. The dark substance termi- nates abruptly with a regular contour, but is not separated from the central mass by any membrane or envelope whatever. The limits are less pronounced, but not wanting, on the side toward the old nucleus. The centre of the clear portion is occupied by a cluster of granules, toward which all the filaments are directed. They stop at the edge of the clear mass; it is exceptional to see a few of the intranuclear filaments send pale prolongations as far as these granules. Rotation of the egg shows that the spindle is flattened so that its cross-section is elliptical, and that the cluster of granules at the centre of the aster has the form of a crescent, and therefore appears in section as a round body of limited extent. Treated with osmic acid, the extranuclear rays are almost obliterated, so that the central mass appears with greater distinctness. In acetic acid the unipolar rays are seen with surprising clearness, and a remnant of the nuclear MUSEUM OF COMPARATIVE ZOOLOGY. 579 envelope becomes visible. This pseudo-membrane surrounds only the middle part of the nucleus; it is wanting at the ends. The grain at the middle of each filament is evidently a simple enlargement of its substance. The unipolar rays are extremely delicate toward their extremities, and at one point are much swollen. Unlike those of the interior of the nucleus, — which are more rounded, distinct, and refringent, and perfectly regular in their arrangement, — these enlargements are elongated, variable in form, and placed at irregular distances from the centre of the aster, so that the enlargements of consecutive filaments never lie adjacent to each other. There may be filaments with two enlargements, others with none. The effect of staining in gold chloride appears to be, to a certain extent, an indication that the view I have expressed about the nature of the spindle fibres at their initiation is erroneous, Fol observes with this treatment that the asters assume a beautiful dark violet color, which at the periphery gradually merges into the color of the yolk, which is of a rose tint. The nucleus and the intranuclear rays, without being de- stroyed, remain pale, — “‘ are not more stained than the rest of the vitellus.” The next phase is characterized by the division of the fibre thickenings, which cannot be observed, however, in the living egg. The vitellus changes form, now in one direction, now in another, but ultimately elongates in the direction of the axis of the amphiaster. In picric acid the enlargements, after division, appear larger and more elongated than in the preceding stage. The interzonal filaments are very pale, and soon disappear ; they are named “ fila- ments connectifs.” The flattening of the amphiaster increases, so that the spindle and areas appear in one position twice as broad as they do after being rotated 90° about the axis of the spindle. The granules of the “area” (sarco- dic mass) are also extended in the same plane in the form of a cylindrical bol- ster, which may be straight or slightly curved. The extranuclear rays form a compact zone around the “ area,” and appear composed of pieces in juxtaposi- tion like the bricks in anarch. ‘Toward the exterior these pieces are continuous with granular rays. This structure is of limited extent, and since it exists at precisely the time when the rays in the living egg extend to the periphery of the yolk, it is to be concluded that the rays consist of two distinct parts, of which one (the central) is brought out by picric acid, while the other (pe- ripheral) is only seen in living eggs. The author cites two figures (Pl. VII. Figs. 9, 11) to illustrate the condition shown at this stage after treatment with acetic acid. The description relates principally to Fig. 11. The nuclear fila- ments are not distinguishable from those of the vitellus, and the granular mass at the centre of the aster, not being discernible, is probably veiled by them ; but the region which extends between the two groups of intranuclear enlargements * is not thus covered ; one should therefore be able to see the filaments which connect these enlargements in pairs,t if they exist. It is easy, * In Fig. 11 no such groups are represented, unless, as the author may possibly have assumed, they are already fused with the “‘ sarcodic mass” at the astral centres. t Fig. 9 shows a spindle with equatorial enlargements ; consequently the ‘‘ con- nective filaments”’ are not to be sought in that stage. 580 BULLETIN OF THE on the contrary, to be assured of the absence of every connective filament in this region ; it is occupied by a uniformly granular vitellus. Since acetic acid has the effect of making all sarcodic filaments so distinct, this fact appears to the author significant [of what ?]. I think no difficulty can be experienced in interpreting Fig. 9 ; it is Fig. 11 which still remains to be explained. I be- lieve it corresponds to my Fig. 82. That the latter does not exhibit a stage subsequent to the formation of the equatorial plate is evident from a comparison with Figs. 90-93. I have assumed that it corresponds to a stage preceding the formation of a veritable spindle. The principal difficulty with this, as with Fol’s interpretation, is in explaining what has become of the substance which usually appears at this time in the form of spindle-fibre thickenings. . To assume, as Fol does, that this substance has already passed through the stages of division and migration, is in contradiction with every other figure he has given. Iam not sure that both these cases may not represent abnormal condi- tions, — either a more complete dissolution and distribution of the substance of the nucleus than is usual, or a failure of the vitellus to respond as promptly as usual to the changes in the nucleus. It is perhaps possible that Fol’s Fig. 11 represents a stage nearly corresponding with that of his Fig. 14 (Pl. VIL.), and that the envelope of the nucleus has simply disappeared a little sooner than usual. In that event, there might be some reason, even in his observations, for retaining the view that the spindle fibres are at first composed of vitelline filaments. But however that may be, further observations are necessary to render either of these figures (Fig. 11 or Fig. 82) satisfactorily intelligible. During the next stage the constriction of the yolk begins, and the second membrane is detached on all sides, although it follows the constriction for a certain distance. The “grains de Bitschli” reach the sarcodic mass of their respective asters, at the edge of which they appear as small spherical bodies, sometimes still arranged in a plane parallel to the equator, sometimes without order. They vary in size and are hollow. At the opposite margin of each “area” is another group of much smaller globules. The latter are still abun- dant, and derived in all probability from the central granular masses of the asters. Ultimately these two groups are intermingled. This may take place before the larger globules have become hollow, or not till after they have in addition each acquired a nucleolus. . ; The stage which follows ends with the separation of the segmentation spheres. The asters continue to move apart and pass the centres of their respective spheres ; the ‘‘areas” have become conical or pyriform. The rays are curved, as already described by Auerbach. The vitelline membrane has failed to fol- low the furrow, and stretches across it from one sphere to the other. In picri¢ acid the larger globules of the “area” are increased in size, and each contains a nucleolus. They are, therefore, true nuclei. The larger they (nuclei) are, the less their number, from which it is probable that they unite with each other. Their arrangement is irregular, The rays on the outer side of the “area” converge toward a point at the external side of the mass ; all the other rays, toward the centre of the mass. In osmic acid the exterior form of the yolk MUSEUM OF COMPARATIVE ZOOLOGY. 581 and its membranes is better preserved than in picric acid. The vitellus as a whole still continues flattened, and the same peculiarity affects the “ areas ”’ and the contained globules. The bodies of the centre of the aster appear small and homogeneous. At first located in the centre, they subsequently approach the young nuclei, with which they ultimately unite. Certain pale corpuscles between the first and second membranes are not polar globules, but result from a precipitate formed in the albuminous fluid by the reagents. The descriptions and figures of the corpuscles which occupy the centre of the aster do not seem to me to afford satisfactory proof of the conclusion, that they are fused with the new nuclei. Figs. 13, 14, of Fol’s Pl. VI. show thickenings in the interzonal filaments. In describing the formation of the polar globules in the Heteropoda, Fol expresses his belief that all the “matieres de rebut” eliminated from the egg correspond to a single cellular element. Here, too, the female pronucleus is formed by a fusion of the central corpuscle of the deep aster with the compact corpuscle formed at the expense of the “‘renflements de Btitschli.” As he has seen only one such corpuscle result from the enlargements, he thinks there is every reason to believe that the supplementary small nuclei (which he finds here) are formed, as in Asterias, independently of the first pronucleus in the substance of the central mass of the internal aster. The first segmentation in the Heteropoda is as follows. The pronuclei be- come mutually flattened, the enveloping layer disappears from the surface of contact. This region of contact is the centre of an irregular system of diver- ging rays extending inside as well as outside the nuclei. This might be mistaken, he says, for the origin of the amphiaster; but by comparisons he has convinced himself that these first radial striae correspond only to the molecular activity which is developed at the moment of the fusion of the nuclei, and that it disappears before the amphiaster arises. However it may be with the Heteropoda, I believe it is not thus with Limax. According to the further description, the plane of union is still visible in Heteropoda after the stars of the amphiaster have appeared. The latter always fall at opposite margins of that plane. At other times the fusion is more complete when the asters arise. 'The pronuclei meanwhile migrate nearly to the centre of the yolk. The contours of the (conjugated) nucleus remain visible up to the moment when the intranuclear enlargements are grouped in the vicinity of the centre of each aster. The middle region of the “filaments connectifs” (PL IX. Figs. 8, 9, 10, Ft) is composed of fine fibrille, which, the author states, have been incorrectly engraved, so that they appear like thickenings of the filaments. The spaces around the centres of the asters are occupied by granular protoplasm exhibiting a radial structure. Perhaps they correspond, he says, to the sarcodic masses which occupy the same position in the sea- urchin, The vitelline filaments of the latter would then correspond to the radial trails of protoplasm which stretch out between the lecithic globules of Pterotrachea. In that event equivalents of the rays immediately around the centre of the aster in the mollusks would not exist in the sea-urchin, or would be invisible by reason of the homogeneous nature of the sarcodic mass. 582 BULLETIN OF THE Compared with the first “amphiaster de rebut,” the present amphiaster is characterized by the absence of vitelline rays, so prominent in the former, and the presence of this granular mass of protoplasm, which is wanting in the other. The axis of this amphiaster is curved, with its concavity directed to- ward the formative pole. It may be that this curvature sustains some relation to a vitelline protuberance which is at this moment visible at the nutritive pole. The author is ignorant of the signification of this protuberance, as he was of that which arises at the formation of the polar globules. In the following stage the groups of fibre thickenings have approached closely the central corpuscle of each aster. The protuberance of the nutritive pole begins to be separated from the vitellus by a circular constriction ; other- wise the yolk is perfectly rounded, and shows no indication of a segmentation furrow. This furrow makes its appearance in the next stage around the vitellus on all sides ; it passes to one side of the protuberance. Bitschli’s corpuscles unite, on both sides, into two or three nuclei, which at once become swollen, and assume the appearance of vesicles, each with an enveloping layer and embra- cing irregular granules. These vesicles, some or all of them, become elongated in the direction of the central corpuscle of the aster, and present an opening like the neck of a bottle, which is extended almost into contact with the cen- tral corpuscle. The vesicles fuse into a single one, having the same form, thick walls and a large corpuscle, which is drawn to a point on the side toward the areal mass. The latter has disappeared, without doubt by absorption into the nucleus, and the contents of the nucleus are in continuity with the clear substance at the centre of the aster, at the expense of which the nucleus seems to grow. While the segmentation is being accomplished and the new nuclei are growing and taking the place of the asters, the protuberance at the vitelline pole gradually disappears by fusing with that one of the spheres of which it formed a part; thus one of the products of segmentation is more voluminous than the other. His researches on Sagitta are especially valuable, since made almost exclu- sively on living eggs. They confirm the results obtained from the study of the Heteropoda. The first sign of the impending division vs the formation of small masses of sarcode at the opposite extremities of the nucleus, which is still intact and spherical. These small masses are optically like the vitelline sarcode, and cause a slight indentation into the cavity of the nucleus, which, though not prominent, is still readily appreciable on account of the perfect sphericity of the rest of the contour. The vitelline rays tend to arrange themselves about se : ; : the extremities of the nucleus in place of converging towards its centre. Thus is quickly produced the dumb-bell stage. The central mass of the asters is perfectly homogeneous. The intranuclear trail differs from the surrounding vitellus only by the presence of the connective striz (interzonal filaments), which are pale and poorly defined. The contents of the new nuclei are clearer and less refringent than their vicinage. The centre of the aster is often occupied by a dark corpuscle. In the interior of the nucleus pale, ill-defined streaks of eee = MUSEUM OF COMPARATIVE ZOOLOGY. 583 protoplasm are seen, which together resemble the tongue of a bell, and are joined with the central substance of the aster. During the second and subse- quent segmentations these streaks of sarcode become at a certain moment much more distinct than during the first segmentation ; they take special forms, which recall the stamens of a flower. There are from four to six of them, but their position is not constant. They attain their greatest distinctness only when the nuclei are so swollen as to be perfectly spherical. Although a mor- phological continuity of these trails (trainées) with the enlargements of the bi- polar filaments appears improbable, it is not absolutely impossible. One might suppose that only a part of the enlargements serve to form the envelope of the young nuclei, and that another part persists under its primitive form [the trails] to become subsequently the intranuclear network. Whatever their ori- gin, these trails of protoplasm disappear during the growth of the new nuclei, and contribute without doubt to the formation of the sarcodic network. The nucleoli make their appearance only a long time after the disappearance of these trails, so that they do not seem to have any direct relation with them. The author arrives at the following conclusions concerning the process of segmentation in general. The first precursory phenomenon is the appearance of a stellate figure, — a radial arrangement of the vitellus, of which the nucleus is the centre. At this moment the nucleus is still intact, but a little less distinct than before ; this appears to indicate that there are movements, — forces which exert their influence at the same time upon the nucleus and upon the vitelline protoplasm. The refringency of the nucleus and the distinctness of its contours are the only things which are modified, up to the moment when the new centres of attrac- tion appear at its opposite poles. The nature of these forces are far from being elucidated, but there are in all cases places where a gradual passage is estab- lished between the nuclear substance and the vitelline protoplasm ; there are therefore points of fusion between the two substances. These centres persist a certain time under the form of corpuscles or of granular masses. The rays of the amphiaster appear at first in immediate contact with the centres, and then stretch out in all directions. They fall into two categories, according as they extend into the interior of the nucleus or into the vitellus. The former are the only ones that are joined end to end. Both kinds bear enlargements ; but those of the extranuclear filaments have no other destination than to add their mass to that of the centre of the aster, while the intranuclear unite in the vicinity of the centre of each aster into one or a small number of corpuscles, which become swollen and unite into a single vesicle, and thus become the origin of the new nuclei. The corpuscles occupying the centre of the star also contribute to the formation of the nuclear elements, which continue to grow at the expense of the sarcodic masses of the asters. The “filaments con- nectifs” remain outside the new nuclei, and do not contribute to their forma- tion. The new nuclei therefore absorb only a part of the substance ‘of the old nucleus, and in return are united with substances which formerly constituted a part of the vitellus. The formation of the polar globules takes place by the 584 BULLETIN OF THE process of cell division. But the second “amphiaster de rebut” arises directly from the internal half of the first. One may compare the two polar globules to a cell originally single. In the cases of superfecundation the union of two male asters to a female pronucleus results in a conjugate nucleus, which soon gives place to a tetraster, in which four equidistant stars occupy the corners of an imaginary square, the sides of which are formed by the intranuclear filaments. In division each of the four groups of filaments (spindles) shows a series of enlargements which divide and migrate as usual. The two groups migrating toward each corner of the square unite to form a single nucleus, so that from the eight groups there result only four nuclei, one to each aster. There are many variations from this more typical condition. Instead of a tetraster there may be a pair of parallel amphiasters, and according as the corresponding asters of these amphiasters are more or less intimately joined by their sarcodic rays, the condition of the tetraster will be more or less closely approached. This is followed by a corre- sponding segmentation into four spheres, which resemble in position the condi- tion after the second normal cleavage. So at subsequent stages there are eight instead of four spherules, etc. In the planula stage the larve are irregular. The formation of a tetraster, and the division into four spheres at once, the author thinks, is not simply an abbreviation of events ; it is a more funda- mental alteration of the normal process. Where there remain male pronuclei which have not become fused with the female, (in cases where several spermatozoa have penetrated the yolk,) sooner or later each of these male pronuclei is resolved into an amphiaster, from which two nuclei arise. When two or three of the male pronuclei have united with a corresponding number of the components of the female pronucleus, and there are others which remain distinct, the conjugated nuclei give rise each to a tetraster, and the superfluous male pronuclei also divide, but with less regu- larity. All eggs embracing independent male asters are very irregular in their seementation. All those which have received more than one spermatozo6n give rise to at least twice as many segmentation spheres as would exist in a normal embryo of the same stage of development, and become monsters. This mon- strosity consists in the repetition of a primitive organ which should normally remain single. Other results have already been given at pages 484 and 491. Fol, rejecting the term “deutoplasm,” introduced by Ed. van Beneden, pro- poses to distinguish the nutritive substances accumulated in the vitellus from those often deposited by the embryo in its interior, and to designate the former as “protolécithe,” the latter as “ deutolécithe.” ‘He proposes further to preserve the term membrane only for the thin layers with double contour, which are harder and more resistant than the protoplasm, and which have lost the ability of remingling themselves directly as living substance with the living protoplasm. He would class under the name of limiting or plastic layers (couches limitantes or plastiques) those which have the peculiarity of following the sarcode in all its changes of form, even the most extreme, and of re-entering directly into the protoplasmic circulation, together Se st eee eee MUSEUM OF COMPARATIVE ZOOLOGY. 585 with those which the protoplasm can easily and instantaneously traverse with- out being first obliged to dissolve them. Limiting layers, which have only a single clear contour, while the other surface passes by insensible transitions into the neighboring substance, may be given the name of “ pellicule.” Fol has also been impressed by the fact, that in the formation of the polar globules the centre of the external aster reaches the surface of the vitellus, and subsequently continues to occupy the most external portion of the globule until the latter is almost detached. Without having observed the curvature of the rays, he remarks that*the aster is of necessity incomplete, and thinks these peculiarities should correspond to a difference (from ordinary cell division) in the mechanism and forces of division. The amphiaster is in some way expelled, pushed by a vis a tergo, instead of operating as two “centres @appel.” Since they subserve no function for vitellus or embryo, and soon suffer disintegration, he prefers the term globules or spherules to that of cells. Granting that there are objections to the use of “globules excrétés,” he claims the justice of the name “corpuscules de rebut.” They are small masses of a substance that has become superfluous, or rather injurious, to the egg, and are for that reason expelled. It is of little significance that this substance has, as germinative vesicle and dot, played an important part in the growth of the ovule, or that its mode of expulsion resembles the division of cells ; they are none the less worn-out materials, and their constancy in the animal kingdom simply tends to show that these substances have become injurious, —an obstacle to “la fécondation intime” and to embryonic development. From all observa- tions it appears that the expulsion of a part of the nucleus of the ovule may be a condition indispensable to the fusion of the pronuclei. If that is the case, one is naturally led to inquire if there are not in the germinative vesicle sub- stances of different affinities or polarities. The combination of these would give a totality which would have no affinity, no attraction, for the male ele- ment. In fact, the zodsperms do not advance toward the interior of the vesicle so long as the latter remains intact. The eliminated substances should, by this hypothesis, have a polarity of the same name as that of the zodsperm, or the same chemical affinities. One could then understand how it is that the presence of a zodsperm in the vitellus hastens the elimination of the polar globules. On the other hand, the penetration of a zodsperm into a polar globule —a fact which has been once or twice observed — would remain inex- plicable. The cause of the obstacle which it seems to offer to fecundation would be seen in its size and inactivity. The expelled portion would be the more passive, the female pronucleus the more active principle. Even if in fecundation it is evident that a zodsperm exercises an influence upon the vitellus from which it is still separated by a relatively large space, the mechanism of that action is not clear. The author sees only three hypotheses which can accord with the facts. The zodsperm may be separated only in ap- pearance ; there may be a continuity of sarcodic substance as soon as the action is exerted. But. as he has found no filament of sarcode extending from the zodsperm toward the vitellus, and no change in the form of the body of 586 BULLETIN OF THE the former, such as must result if such a filament exists, it only remains to assume pre-existing filaments which arise from the surface of the vitellus. These might, a priori, be represented as extremely delicate filaments traversing the odlema in radial lines; but as they have never been discovered in the hardened or living egg, it is necessary to deny their existence. The second hypothesis is that the action of the vitellus is in response to a pressure exerted " by the zodsperm upon the intervening portion of the striate envelope through which it endeavors to advance. As the vitellus does not react upon the press- ure of all kinds of bodies, it is necessary to admit that there is some peculiar- ity, — some special rhythm arising from the undulations of its cue. But it is difficult to understand how this pressure could be appreciated through half the _thickness of the odlema, or communicated to a definite extent of the vitelline surface, or why the cone of attraction should arise exactly opposite the most advanced zodsperm. ‘The last supposition consists in admitting an attraction, the nature of which is unknown, which exercises an influence not only by im- mediate contact, but also at a slight distance ; although this hypothesis itself needs to be explained. The composition of the cone of attraction is not better understood. Is it a substance secreted by the vitellus, or a prolongation of the vitelline sarcode, and, in the latter case, is it an accumulation of the superficial - limiting layer, or of the deeper layer? The first hypothesis is excluded, in the author’s opinion, by the case where the protuberance is of considerable volume, and the continuity of its substance with the vitelline sarcode is evident, but between the other two hypotheses he remains undecided. The cone of exu- dation, on the other hand, is only a liquid, slightly refringent substance, without cohesion, which is ejected or excreted by the surface of the yolk. Fol distinguishes three kinds of centres of attraction, — the male, the female, and those which preside at segmentation. The male centre takes its origin in a spermatozoon,* whose “ body” becomes the centre of an aster and the point of departure in the formation of the male pronucleus. I am not certain what he means by that part of the statement which I have italicized, since he has shown more clearly than any one else that the male aster does not always centre at the middle of the male pronucleus. I can reconcile this statement with the fact mentioned only by assuming, either that he thinks the male pro- nucleus is formed eccentrically to the head of the spermatozoon, or that this statement is only intended to be an approximate expression of facts. The former assumption is the less probable, because he adds : “ It is important not to forget that the body of the spermatozoén is no longer intact at the moment when these phenomena (astral) appear; it has changed form and has in- creased in size by the absorption of vitelline sarcode.” I therefore think the * The author thinks recent observations tend to-show that the spermatozoon is formed of cellular protoplasm, to the exclusion of the substance of the nucleus. Conse- quently the male pronucleus is formed by the union of two protoplasms, which have not suffered a single admixture of the substance of preformed nuclei. ‘‘ Le pronu- cléus male ne descend & acun titre, pas méme en partie, d’un noyau plus ancien ; il est de formation nouvelle.” MUSEUM OF COMPARATIVE ZOOLOGY. 587 author has attached far too little importance to his observations on Sagitta (Pl. X. Fig. 6). He remarks that the attraction is therefore exercised not so much by a simple spermatozo6on as by a fusion of this with the sarcode, and that it is this union which gives rise to the male pronucleus. This statement approaches so closely the view I have already advocated, that I should be in- clined to think our ideas on this point identical, were it not that he sub- sequently explains his position in a manner which shows clearly that in his opinion it is the substance of the male pronucleus which exercises the attractive influence rather than a force liberated in the act of the union. He says, sub- stantially : “ The male center is surrounded soon after its formation by a star of unipolar rays. Shortly the centre, represented by the body of the more or less modified spermatozo6n, is surrounded with clear protoplasm. This mass continues to increase, —a fact which seems to indicate that the sarcodic rays are the expression of centripetal currents of protoplasm coming from the vitel- lus. However that may be, it is certain that the aster is formed around a modified spermatozoén which is found at its centre ; that it is a result of the action exercised by this corpuscle upon the surrounding vitellus. If this is so, it should be explained why the evidence of this attraction ceases when the nucleus has attained its maximum size. The phenomena of attraction, Fol continues, are perhaps less striking for the female than for the male pronucleus, but they exist none the less. They are, —(1.) radial lines, which continue to augment in proportion as the pro- nucleus absorbs vitelline sarcode, and are only effaced at the moment when it has come to rest ; (2.) the centripetal advance of sarcodic currents, of which the radial strize are the visible expression, and the direction of which is indicated by the growth of the nucleus ; (3.) the displacement of the pronucleus itself from the periphery toward the centre of the yolk. The centres of attraction which appear at the poles of the amphiaster of segmentation are due to a fusion (rencontre et alliage) of nuclear substance with vitelline sarcode at the circumscribed points (poles) where the contour of the elongated nucleus becomes lost. But this is not the first process pre- liminary to the formation of the amphiaster. On the contrary, in the case of the sea-urchin the appearance of a mass of sarcode around the nucleus, as well as the “pinnate figure,” precedes. The latter appears to be the expression of centrifugal rather than centripetal currents; the formation of typical asters, on the other hand, only dates from the moment when the nuclear and vitelline substances enter into communication at the poles of the nucleus. The three cases have in common this point: that the phenomena of attraction (and of repulsion) may precede the mingling of two diverse substances, but that they attain their full development, and interpret themselves by the formation of a veritable aster, only when there has been a fusion of the two substances ; the point of fusion is then always the centre of the system of rays. It seems to me this last statement is more in harmony with the view I have maintained than it is with the ideas which Fol has himself previously advocated. In my - opinion it is the point of fusion, and not necessarily the product of the fusion, 588 BULLETIN OF THE which marks the centre-of attraction ; it is the force set free in the act of fu- sion, not the affinity of the already formed nucleus for other matter, which induces the radiate appearance. If this view is justified, it seems to me that it would not be necessary to make a special case of Sagitta,.and to hesitate, as Fol does (p. 259), in comparing the structure which he there calls by the non-committal name “la vacuole” with the male pronucleus of other animals.* I have less hesitation in pronouncing this “vacuole” in every essential the equivalent of the male pronucleus of other animals, as I have seen something so nearly identical in Limax (see Fig. 68), where the staining of the structure in question banishes all doubt as to its nuclear character. I must confess, moreover, that I am considerably puzzled to know what Fol means by this hesitancy, as I see no other possible explanation in view of the ultimate fate of this vacuole. Instead of presenting any difference of primary, or even sec- ondary importance, it seems to me a very welcome confirmation of the substan- tial identity of the astral phenomena which accompany the male pronucleus and those which preside at the subsequent segmentations.f In regard to the nature of the rays, the author says, the hypothesis of a simple polar attraction which arranges the vitelline granulations in a certain order without displacing them is not defensible ; for these bands are in all cases broader than the mean distance of the lecithic granules. These fila- ments, so distinct in acetic acid, do not admit the belief in a simple polari- zation of molecules. The accumulation of clear protoplasm around the nucleus and its poles could not take place without currents of this viscid substance, But if there are currents, in what direction are they produced? In the sea- urchin, before the formation of the amphiaster, the perinuclear mass moves toward the equator, and becomes a disk at the moment when the pinnate arrangement of the clear streaks becomes visible. Here it may well be that the currents arising in the equatorial region proceed beyond the poles to spread their substance in the vitellus. During the division of the amphiaster the facts appear to favor the supposition of centripetal currents.. The centripetal movement of the thickenings [in the unipolar rays] which are rendered visible by acetic acid, and the continuous growth of the central masses, appear to indi- cate a slow advance of the sarcode toward the centre of the aster. Nevertheless, observations on other objects must, he says, be taken into the account. Auerbach’s theory of a dispersion of nuclear fluid is untenable, since the asters are formed before the volume of the nucleus is diminished. On the other hand, Flemming has seen pseudopodia at the surface of the polar globule in Anodonta, of which the following explanation is offered. From the figures J * “‘Chez Sagitta, par exemple, nous avons vu que l’aster traine a sa suite une sorte de vacuole toujours croissante ; le centre de l’aster se trouve au bord allongé de cette vacuole, toujours du cdté vers lequel elle se dirige. C’est done dans l’aster et dans son centre que réside la force motrice, tandis que la vacuole, que j’hésite du reste 4 comparer au pronucléus des autres animaux, est trainée a sa suite.” t P. S. — May it not be that this is a typographical error, and that the negative has been inadvertently omitted ? MUSEUM OF COMPARATIVE ZOOLOGY. 589 (Flemming’s) it is to be seen that the polar globule is half formed at this time, and consequently “ Biitschli’s corpuscles” are already divided. As is known, the external aster is incomplete, its centre having arrived at the surface and being only partly surrounded by unipolar filaments. It is therefore natural to presume, he says, that the pseudopods correspond to unipolar filaments, which are wanting in consequence of the superficial position of the aster. If this rea- soning is correct, he adds, this is a case where the filaments are elongated in a centrifugal direction during a part of the period of division, to be subsequently retracted. If the pseudopodia belonged to a somewhat ae phase, I should think there would be greater justice in this conclusion. The position of the rays after the division of the equatorial zone, as shown in Limax, Fig. 50, does not seem easily reconcilable with Fol’s interpretation. But the observations of Strasburger on Spyrogyra also tend, continues the author, to establish the existence of centrifugal currents during the division of the amphiaster. If, now, we compare the unipolar filaments with these pseudopodal filaments (Spirogyra), the former should be considered as streaks of sarcode stretching out toward the periphery, but having the opposite course after the division of the intranuclear enlargements. The changes within the nucleus are also instructive. The formation of the - spindle from the intranuclear network and the division and migration of the fibre thickenings appear to result from an action exercised upon the interior of the nucleus by two centres placed at its poles. It is not possible to say what the nature of this action is. An internal repulsion would not explain the eccentric position of the “amphiaster de rebut.” A simple attraction would not explain the formation of Biitschli’s corpuscles. On the other hand, the last part of the act of division, the formation of new nuclei, appears explainable upon the hypothesis of an attraction exerted by the centres upon their vici- nage, and of the mutual repulsion of the asters. A central attractive influence on the part of the new nuclei would explain the process of segmentation, ex- cept in the case of the polar globules. The evidences of the existence of repulsions are the progressive separation of the poles of the amphiaster and the mutual repulsion of the male asters. After the female pronucleus has been superfecundated the conjugated nucleus and the independent male asters are all situated at the external third of vitelline rays. This regularity of situation indicates that they occupy a position of equilibrium between opposing forces, and these forces can only be an attraction toward the centre of the yolk on the one hand, and a mutual repulsion on the other. The attraction between the sexual nuclei is a special case in which this force is very evident. The motion of the male aster is correlated with the position of the female pronucleus; it has not a constant relation with the vitellus. In the further development, the rhale elements exercise a preponderating influence, as the existence of the tetraster after fusion with more than one zoosperm shows; the isolated male asters pass through the stages of amphi- astral division, but the isolated (unfecundated) female pronucleus decomposes without exhibiting any of these changes. 590 BULLETIN OF THE The male pronucleus arises when a living zoésperm penetrates into a mature and living vitellus. In certain cases (sea-urchin) it is not much larger than the “body” of a zodsperm, and one might then entertain the opinion that it is only sucha “body” swollen. It then forms the centre of an aster. In other cases (Heteropoda) it becomes as large as the female pronucleus, and is not sur- rounded by a radial figure.* This growth is not a simple inflation of the body of a zodsperm by a liquid, because when fully developed it contains many times the original quantity of protoplasmic substance ; it is not a process of nutrition, a digestion of vitelline substance, since that physiological process is complicated and requires a considerable time for its accomplishment, while the absorption of vitelline substance is direct and prompt. The male pronucleus is therefore a product of the union of spermatic protoplasm with vitelline pro- toplasm, and from this fusion results a nuclear body possessing a multitude of properties which are wanting to the isolated zojsperm. Likewise the female pronucleus, which has its first origin in the “ corpuscules de Biitschli” belonging to the internal half of the second “ amphiaster de rebut,” is derived for the greater part from vitelline sarcode. The disproportion be- tween nuclear and vitelline substances in this case is fully as great as between the body of the zodsperm and the completed male pronucleus in the Hetero- poda. Finally, the cleavage nuclei are formed at the expense of the “central masses” and of the intranuclear varicosities of the old nucleus. These “masses” may also descend, in part at least, from the old nucleus. But even here the substance derived from that source is only a fraction of the whole mass of the new nuclei. Besides, a part of the substance of the old nucleus remains en route under the form of the “trainée internucléaire,” and does not enter into the composition of the new cytoblasts. A consideration of the origin of the nucleus in these three cases leads to the same conclusion, that its substance comes in part from a pre-existing nucleus or a foreign element, and in part from the protoplasm of the cell, —the latter by _ way of fusion, not of nutrition. The young nucleus while still quite small exercises a strong influence on the surrounding vitellus. In proportion as it increases in size, this influence diminishes, and once completed, it ceases to ex- ist. It therefore seems permitted to conclude that the attraction or influence exercised by the young nucleus increases in proportion as it is fused with cell protoplasm, and subsequently diminishes when the proportion of the latter element is too great. There would be a period of activity followed by a period of saturation ; the latter would supervene as soon as the nucleus attained the limit of its growth. I can omit a presentation of the author’s “ Théorie électrolytique des Mouve- ments protoplasmiques,” with which he ‘terminates his paper, since it is not directly applied to an elucidation of the phenomena under consideration. * The author has previously stated, I believe, that in the Heteropoda the male pronucleus is surrounded by rays in the living egg. See p. 577. 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VI., VIL, IX. 14 Sept. 1854. ’54*. Beitrage zur Anatomie und Physiologie von Mermis albicans. (6 Aug. 1853.) Zeitschr. f. wiss. Zool., Bd. III. Hefte 2 u. 3, pp. 207-284, Taf. XI-XV. 19 Dec. 1853. ’56. Ueber die Befruchtung des Hies von Echinus esculentus. Verhandlg. d. naturf. Gesellsch. in Basel, Bd. I. Heft 3, pp. 374, 875. 1856. Metschnikoff, Elias. ’66. Embryologische Studien an Insecten. Zeitschr. f. wiss. Zool., Bd. XVI. Heft 4, pp. 389-500, Taf. XXIII.-—XXXII. 6 Dec. 1866. 69. Studien tiber die Entwickelung der Echinodermen und Nemertinen. (18 Mar. 1869.) Mém. de l’Acad. imp. des Sci. de St. Pétersbourg, 7 sér., Tom. XIV. No. 8, 73 pp., 12 Taf. 69%. Separate, with above title. 2+ 73 pp, 12 Taf. 1869. '74. Studien tiber die Entwickelung der Medusen und Siphonophoren. 608 BULLETIN OF THE (5 July, 1872.) Zeitschr. f. wiss. Zool., Bd. XXIV. pp. 15-83, Taf. II.- XIL., 8 Holazschn. 12 Feb. 1874. Minot, Charles Sedgwick. "77°, Account of the Recent Investigations of Embryologists on the Forma- tion of the Germinal Layers and of the Phenomena of Impregnation among Animals. Proc. Bost. Soc. Nat. Hist., Vol. X1X., pp. 165-171. 18 Apr. 1877. Miiller, A. ’64. Ueber die Befruchtungserscheinungen im Hi der Neuenaugen. Schrif- ten d. k. phys-dkonom. Gesellsch. zu Konigsberg, Jahrg. V. pp. 109- 419. 1864. Miiller, Friedrich. 48. Zur Kenntniss des Furchungsprocesses im Sehneckeneie. Arch. f. Na- ture., dabre, XTV. Bd. T. pp. 1-6, Tat) EP aaisas, Miiller, Johannes. ’52. Ueber die Erzeugung von Schnecken in Holothurien. Arch. f. Anat. Physiol. u. wiss. Med., Jahrg. 1852, pp. 1-36. 52%. Ueber Synapta digitata und tber die Erzeugung von Schnecken in Holothurien. iv + 36 pp., 10 Taf. Berlin: G. Reimer. 1852. Munk, Hermann. 58. Ueber Ei- und Samenbildung und Befruchtung bei den Newauides (Apr. 1858.) Zeitschr. f. wiss. Zool., Bd. IX. Heft 3, pp. 365-416, Taf. XIV., XV. 11 Oct, 1858. Oellacher, Josef. "70. Untersuchungen itiber die Furchung und Blatterbildung im Hihnereie. Studien aus dem Institute fiir experimentelle Pathologie, herausg. von 8. Stricker. I. Wien. 1870. 72. Beitrage zur Geschichte des Keimblaschens im Wirbelthiereie. Arch. f. mik. Anat., Bd. VIII. pp. 1-27, Taf. 1. 1872. "72. Beitrage zur Entwicklungsgeschichte der Knochenfische nach Beobach- tungen am Bachforelleneie. Zeitschr. f. wiss. Zool., Bd. XXII. Heft 4, pp. 373-421, Taf. XXXIT., XXXITI. 20 Sept. 1872. "74, Ueber eine im befruchteten Forellenkeim vor den einzelnen Furchungs- acten zu beobachtende radiare Structur des Protoplasma. Berichte d. naturw.-med. Verein zu Innsbruck, Bd. IV. 1874: (?). Peremeschko. 78. Ueber die Theilung der Zellen. Vorlaufige Mittheilung. Centralbl. f. d. med. Wissensch., Jahrg. XVI. No. 30, pp. 547, 548. 27 July, 1878. "78°, Ueber die Theilung der thierischen Zellen. (Preliminary communication in Russian.) Medicin. Bote. 1878, No. 31. 5 Aug. 1878. "78°, Rev. by Ebner iz Hofmann u. Schwalbe’s Jahresberichte, Bd. VIL, Anat. Abth., p. 15: Pérez, J. 77, Sur la fécondation de l’ceuf chez l’Oursin. Compt. rend. de P Acad. des Sci. Paris, Tom. LXXXIV. No. 13, pp. 620-622. 26 Mar. 1877. {es gros x — eg ——— “ 5 - x PS ete os a eee Seas ae ss ee. MUSEUM OF COMPARATIVE ZOOLOGY. 609 '77°. Observations relatives aux opinions émisse par M. H. Fol, le 23 juillet dernier, sur la fécondation de l’ceuf chez l’Astérie et chez l’Oursin. Compt. rend. de l’Acad. des Sci. Paris, Tom. LXXXV. No. 6, pp. 353, 354. 6 Aug. 1877. '79. Recherches sur les phénoménes qui précedent la segmentation de Pceuf chez |’Hélice (H. aspera). Jour. de Anat. et de la Physiol., Vol. XV. pp. 329-401, Pl. XXVII., XXVIII... Aug. 1879. Pfliger, E. F.,.W. ’63. Ueber die Hierstocke der Saiugethiere und des Menschen. 124 pp., 5 Taf. Leipzig: Engelmann. 28 Mar. 1863. Priestley, John. "76. Recent Researches on the Nuclei of Animal and Vegetable Cells, and especially of Ova. Quart. Jour. of Mic. Sci., n. ser., Vol. XVI. pp. 131- 152, Pl. XI., XII. Apr. 1876. Purkinje, Joan. Evang. 30. Symbole ad ovi avium historiam ante incubationem. Adjecte sunt tab. due lith. Lipsie: L. Voss. 1830. Quatrefages, Armand de. ’48. Etudes embryogéniques. Mémoire sur l’embryogénie des Annélides. Ann. des Sci. nat., 3 sér., Zool., Tom. X. pp. 153-201. 1848. Rabl, Carl. '75. Die Ontogenie der Siisswasser-Pulmonaten. Jena. Zeitschr., Bd. IX. pp. 195-240, Taf. VII.-IX. 1875. '76. Ueber dic Entwicklungsgeschichte der Malermuschel. Jena. Zeitschr., Bd. X. pp. 310-393, Taf. X.- XII. 31 Aug. 1876. Ratzel, Fritz. 69. LBeitrage zur anatomischen und systematischen Kenntniss der Oligo- chaeten. Zeitschr. f. wiss. Zool., Bd. XVIII. Heft 4, pp. 563-591, Taf. XLII. 1 Feb. 1869. 69". Vorlaufige Nachricht iber die Entwickelungsgeschichte von Lumbricus u. Nephelis. (13 Aug. 1868.) Zeitschr. f. wiss. Zool., Bd. XIX. Heft 2, pp. 281-283. 1 July, 1869. Ratzel, Fritz, und M. Warschawsky. ‘69. Zur Entwickelungsgeschichte des Regenwurms (Lumbricus agricola Hoffm.). Zeitschr. f. wiss. Zool., Bd. XVIII. pp. 546-562, Taf. XLI. 1 Feb. 1869. Reichert, Karl Bogislaus. 46. Der Furchungsprocess und die sogenannte Zellenbildung um Inhaltspor- tionen. Arch. f. Anat. Physiol. u. wiss. Med., Jahrg. 1846, pp. 196-282, Taf. IX. 1846. '47. Beitrag zur Entwickelungsgeschichte der Samenkorperchen bei den Ne- matoden. Arch. f. Anat. Physiol. u. wiss. Med., Jahrg. 1847, pp. 88 - 147, Taf. VI. 1847. 56. Ueber die Micropyle der Fischeier und tiber einen bisher unbekannten, eigenthiimlichen Bau des Nahrungsdotters reifer und befruchteter Fischeier VOL. VI.— NO. 12. 39 ‘ 610 BULLETIN OF THE (Hecht). Arch. f. Anat. Physiol. u. wiss. Med., Jahrg. 1856, pp. 83 - 124, Taf. II., III., und IV. Figs. 1-4. 1856. Remak, Robert. ’55. Untersuchungen tiber die Entwickelung der Wirbelthiere. vi + xxxviii + 195 pp., 12 Taf. Berlin: G. Reimer. 1850, 1851, 1855. Repiachoff, W. '78. Ueber die ersten embryonalen Entwicklungsvorgange bei Tendra zoste- ricola. (Dec. 1877.) Zeitschr. f. wiss. Zool, Bd. XXX., Supplem., Heft 3, pp. 411-423, Taf. XIX. 28 May, 1878. Robin, Charles Philippe. ’62. Mémoire sur les phénoménes qui se passent dans l’ovule avant la seg- mentation du vitellus. Jour. de la Physiol, Tom. V. No. 17, pp. 67- 109.: Jan. 1862. ie 62>, Mémoire sur les globules polaires de l’ovule et sur le mode de leur pro- duction. Compt. rend. de lAcad. des Sci. Paris, Tom. LIV. pp. 112 - 116. 1862. ’62°. Mémoire sur la production des cellules du blastoderme sans segmenta- tion du vitellus chez quelques articulés. Compt. rend. de l’Acad. des Sci. Paris, Tom. LIV. pp. 150-153. 1862. ’62°, Mémoire sur les globules polaires de Povule. (Lua Acad. des Sci. le 11 Jan. 1862.) Jour. de la Physiol., Tom. V. No. 18, pp. 149-190, Pl. I1.-V. Apr. 1862. 62°. Note sur la production du noyau vitellin. Jour. de la Physiol., Tom. V. No. 19, pp. 309-323. Juillet, 1862. ’62'. Mémoire sur la production du blastoderme chez les Articulés. (Lu a Acad. des Sci. le 20 Jan. 1862.) Jour. de la Physiol., Tom. V. No. 19, pp. 348-383, Pl. VII. July, 1862. ‘75. Mémoire sur le développement embryogénique des Hirudinées. Mém. de Acad. des Sci. Paris, Tom. XL. 472 pp., 19 pl. 1875. Russow, Edmund. '72. Vergleichende Untersuchungen betreffend die Histologie (Histogra- phie und Histogenie) der vegatativen u. sporenbildenden Organe u. die Entw. der Sporen der Leitbiindel-Kryptogamen, mit Bericksichtigung der Histologie der Phanerogamen, ausgehend von der Betrachtung der Mar- siliaceen. (Presented Apr. 6, 1871.) Mém. de l’Acad. imp. des Sci. de St. Pétersbourg, Tom. XIX. No. 1, vi + 207 pp., Taf. 1.-XI. 1872. Salensky, W. 74°, Ueber den Bau und die Entwickelungsgeschichte der Amphilina Wagn. (Monostomum foliaceum Rud.). Zeitschr. f. wiss. Zool., Bd. XXIV. pp. 991-342, Taf. XXVILTI.—-XXXII. 16 Sept. 1874. 76. Embryonale Entwicklungsgeschichte der Salpen. Zeitschr. f. wiss. Zool., Bd. XXVII. Heft 2, pp. 179-237, Taf. XIV.-XVI. 23 June, 1876. Sars, Martin. ’37. Zur Entwickelungsgeschichte der Mollusken und Zoophyten. Arch. f. Naturg., Jahrg. III. Bd. I. pp. 402-407. 1887. MUSEUM OF COMPARATIVE ZOOLOGY. 611 Schenk, S. L. '73. Die Hier von Raja quadrimaculata (Bonap.) innerhalb der Hileiter. (Sitz. ungsb. d. k. Akad. der Wissensch. Wien, Mathem-naturw. Cl., Bd. LXVIII. Abth. 1, pp. 363-374, 1 Taf. 18 Dec. 1878. "74. Der Dotterstrang der Plagiostomen. Sitzungsb. d. k. Akad. der Wis- sensch. Wien, Mathem-naturw. Cl., Bd. LXIX. Abth. 1, pp. 801-308, 1 Taf. 26 Mar. 1874. 74°. Entwickelungsvorgange im Hichen von Serpula nach der kiinstlichen Befruchtung. Sitzungsb. d. k. Akad. der Wissensch. Wien, Mathem- naturw. Cl., Bd. LXX. Abth. 3, pp. 287-301, 1 Taf. 1875. '76. Die Vortheilung des Farbstoffes im Hichen wahrend des Furchungspro- cesses. Sitzungsb. d.k. Akad. der Wissensch. Wien, Mathem-naturw. CL., Bd. LXXIII. Abth. 3, pp. 112-120, 1 Taf. 17 Feb. 1876. 77. Bemerkungen iiber den Keimfleck. Mittheilg. embryol. Institut zu Wien, Bd. I. Heft 1, No. V. pp.55-61. 1 Feb. 1877. Schleicher, W. '78. Ueber den Theilungsprozess der Knorpelzellen. Vorlaufige Mitthei- lung. (27 May, 1878.) Centralbl. f. d. med. Wissensch., Jahrg. XVI. No. 23, pp. 418, 419. 8 June, 1878. '78. Die Knorpeltheilung. Ein Beitrag zur Lehre der Theilung von Ge- webezellen. (Aus dem histologischen Laboratorium in Gent.) Arch. f. mik. Anat., Bd. XVI. pp. 248 - 302, Taf. XII.-XIV. 20 Dec. 1878. Schmidt, Oscar. 51. Ueber die Entwickelung von Limax agrestis. Arch. f. Anat. Physiol. u. wiss. Med., Jahrg. 1851, pp. 278-290, 1 Taf. 1851. Schmitz, Fr. '79. Beobachtungen tiber die vielkernigen Zellen der Siphonocladiaceen, pp. 273-320, Taf. XII. Festschrift zur Feier des hundertjahrigen Bestehens der Naturf. Gesellsch. in Halle, a. 8., 342 pp., 12 Taf. Halle: Max Nie- meyer. 1879. Schneider, Anton. '73. Untersuchungen tiber Platthelminthen. 14 Jahresbericht der oberhes- sischen Gesellschaft fir Natur- und Heilkunde, pp. 69-140, Taf. ILI. -VII. Giessen, April, 1873. Schultz, Alexander. ‘75. Zur Entwickelungsgeschichte des Selachiereis. (Jan. 1875.) Arch. f. mik. Anat., Bd. XI. pp. 569-582, Taf. XXXIV. 1875. Schultze, Max Sigismund. ’65. Zur Kenntniss der Leuchtorgane von Lampyris splendidula. Arch. f. mik. Anat., Bd. J. pp. 124-137, Taf. V., VI. 1865. Schulze, Franz Eilhard. '74*. Rhizopodenstudien, IJ. Arch. f. mik. Anat., Bd. X. pp. 377 - 400, Pat 2 VI, AVIL. 1874: '75°. Ueber den Bau und die Entwicklung von Sycandra raphanus, Haeckel. Zeitschr. f. wiss. Zool., Bd. XXV., Supplem., pp. 247 -260, Taf. XVIII. - XXI. 22 Dec. 1875. 612 BULLETIN OF THE Schwalbe, G. 68. Ueber den Bau der Spinalganglien nebst Bemerkungen tiber die sympa- thischen Ganglienzellen. Arch. f. mik. Anat., Bd. IV. pp. 45-72, Taf. LVS) VAS68. '76. Bemerkungen iiber die Kerne der Ganglienzellen. (May, 1875.) Jena. Zeitschr., Bd. X. Heft 1, pp. 25-40, 2 Holzschn. 15 Feb. 1876. Selenka, Emil. 75. Hifurchung und Larvenbildung von Phascolosoma elongatum, Kef. Zeitschr. f. wiss. Zool., Bd. XXV. Heft 4, pp. 442-450, Taf. XXIX., XXX. 25 July, 1875. ‘76%. Zur Entwickelung der Holothurien (Holoth. tubulosa u. Cucumaria doliolum). in Beitrag zur Keimblattertheorie. Zeitschr. f. wiss. Zool., Bd. XX VII. Heft 2, pp. 155-178, Taf. 1X.-XIII. 23 June, 1876. 78. Beobachtungen iiber die Befruchtung und Theilung des Kies von Toxo- pneustis variegatus. Vorlaufige Mittheilung. (June, 1877.) Sitzsungsh. d. phys.-med. Gesellsch. zu Erlangen, Heft X. pp. 1-7. 1878. '78*. Zoologische Studien. I. Befruchtung des Hies von Toxopneustis varie- gatus. in Beitrag zur Lehre von der Befruchtung und Eifurchung. vi +18 pp. Leipzig: Wm. Engelmann. 1878. Semper, Carl. ’57. Beitrage zur Anatomie und Physiologie der Pulmonaten. Zeitschr. f. wiss. Zool., Bd. VIII. Heft. 3, pp. 340-399, Taf. XVI., XVII. 12 Nov. 1856. "75. Ueber die Entstehung der geschichteten Cellulose-Epidermis der Asci- dien. Arbeiten a. d. zool.-zoot. Institut in Wurzburg, Bd. II. pp. 1-24, 6 VTi Od SS '75°. Das Urogenitalsystem der Plagiostomen und seine Bedeutung fir das der ibrigen Wirbelthiere. Arbeiten a. d. zool.-zoot. Institut m Wirz- burg, Bd. IL. pp. 195-509, Taf. X.-XXIT. 1875. Spengel, J. W. "76. Das Urogenitalsystem der Amphibien. Arbeiten a. d. zool.-zoot. Insti- tut in Wirzburg, Bd. III. Heft 1, pp. 1-114, Taf. I.-1V. 1 July, 1876. Stecker, Anton. 76°. Ueber die Entwickelung der Chthonius-Hier im Mutterleibe, und die Bildung des Blastoderms. Sitzungsb. der k. bohm. Gesellsch. der Wis- sensch. Prag., Jahrg. 1876, No. 3, pp. 122-135, 7 fig. 24 Mar. 1876. "76°. Transl. by W.S. Dallas iz Ann. and Mag. of Nat. Hist., ser. 4, Vol. XVIII. No. 105, pp. 197 — 207, 7 fig. Sept. 1876. Stilling, B. ’56. Anatomische und mikroskopische Untersuchungen ttber den Bau der Nervenprimitivfaser und der Nervenzelle. 11+ 152 pp.,2 Tab. Frank- furt a. Main: J. Riitten. 1856. ’56—’59. Neue Untersuchungen iiber den Bau des Riickenmarks. Frank- furt a. Main: J. Riitten. Cassel: H. Hotop. 20+ 1192 + 108 pp. 1856-1859. MUSEUM OF COMPARATIVE ZOOLOGY. 613 Stossich, Michele. "76. Sopra lo sviluppo delle serpule. Boll. Soc. Adriat. di Sci. nat., Vol. IL. No. 3, pp. 276-282, Tav. I. 1876. ‘77. Transformazione della vescica germinativa e sua importanza nella seg- mentazione del tuorlo. (9 July, 1877.) Boll. Soc. Adriat. di Sci. nat., Vol. III. pp. 212-239, Tav. L., IL. Strasburger, Eduard. "75. Ueber Zellbildung und Zelltheilung. (May, 1875.) Jena: Hermann Dabis. 1875. "76. Same. ‘Zweite verbesserte und vermehrte Auflage nebst Untersuchun- gen iiber Befruchtung, 12 + 382 pp., Taf. 1.- VIII. Mar. 1876. "76". Studien iiber das Protoplasma. Jena. Zeitschr., Bd. X. Heft 4, pp. 395 - 446, Taf. XIII., XIV. Oct. 1876. 77. Ueber Befruchtung und Zelltheilung. (Aug. 1877.) Jena. Zeitschr., Bd. XI. Heft 4, pp. 435 -536, Taf. XXVII.-XXXV. 10 Dec. 1877. Stricker, S. 77. Beobachtungen iiber die Entstehung des Kerns. Sitzungsb. d. k. Akad. der Wissensch. Wien, Mathem.-Naturw. Cl., Bd. LXXVI. Abth. 3, pp. 7 228. 7 June, 1877. Torok, Aurel v. "74. Rolle der Dotterplattchen beim Aufbau der Gewebe. Centralbl. f. d. med. Wissensch., Jahrg. XII. No. 17, pp. 257-261. 4 Apr. 1874. '77. Ueber formative Differenzirungen in den Embryonalzellen von Siredon pisciformis. Hin Beitrag zur Histogenese des Thierorganismus. (23 Sept. 1876.) Arch. f. mik. Anat., Bd. XIII. Heft 4, pp. 756-783, Taf. XLIV. S377. Treub, M. ’'79. Quelques recherches sur le réle du noyau dans la division des cellules végétales. Akad. van Wetenschappen, Amsterdam, Deel XIX. 35 pp., 4pl. 1879. Trinchese, Salvatore. '76. Sulla rete protoplasmatica della vescicola germinativa. Rendiconto dell’ Accad. Sci. dell’ Istit. di Bologna, Annata 1875-76, pp. 51,52. 13 Jan. 1876. '76%, Anatomia della Caliphylla mediterranea. Mem. dell’ Accad. Sci. dell’ Istit. di Bologna, 3 ser., Tom. VII. fase. 2, pp. 173-192, 2 Tav. 30 Mar. 1876. 76. Sulla struttura della cellula animale. Rendiconto dell’ Accad. Sci. dell’ Istit. di Bologna, Annata 1875-76, pp. 122,123. (See also p. 70.) 27 April, 1876. '77, Sulla struttura dell’ uovo dei mammiferi e dei molluschi. Rendiconto dell? Accad. Sci. dell’ Istit. di Bologna, Annata 1876-77, pp. 36, 37. (See also p. 156.) 4 Jan. 1877. Tschistiakoff, J. '75. Beitrage zur Physiologie der Pflanzenzelle. Kurze Notizen und vor- 614 BULLETIN OF THE laufige Mittheilungen iiber die Entwickelung der Sporen und des Pol- lens. (14 July, 1874.) Botanische Zeitung, Jahrg. 33, Nos. 1, 2, 3, 6, 7, pp. 1-8, 17-26, 83-38, 81—88)97 —103, Tata. 2,8; 16 Janieo ae Feb. 1875. Turpin, J. F. 32. Analyse microscopique de Pout du Limagon. Ann. des Sci. nat., Tom. XXV. pp. 426-455. 1832. Villot, A. '74. Monographie des Dragonneaux (Genre Gordius, Dujardin). (4 Feb. 1874.) Arch. de Zool. exp. et gén., Tom. III. pp. 39-72, 181-238, Pl Via ee VLU Xe alee Vogt, Carl. ’42. Untersuchungen tiber die Entwickelungsgeschichte der Geburtahalfer: krote (Alytes obstetricans), x +134 pp., 3 Taf. Solthum: Jent u. Gassmann. 1842. Wagener, Guido. ’57. Ueber den Zusammenhang des Kernes und Kernkérpers der Ganglien- zelle mit dem Nervenfaden. Zeitschr. f. wiss. Zool., Bd. VIII. Heft 4, pp. 455-458, Taf. XXI. 26 Feb. 1857. Walter, Georg. 58. Fernere Beitrage zur Anatomie und Physiologie von Oxyuris ornata. Zeitschr. f. wiss. Zool., Bd. IX. Heft 4, pp. 485-495, Taf. XIX. 20 Dec. 1858. Warneck, Nicolas Alexander. 50. Ueber die Bildung und Entwickelung des Embryos bei Gasteropoden. Bull. Soc. impér. des Naturalistes de Moscou, Tom. XXIII. No. 1, pp. 90 ~ 194, Taf. Tl. -—TV., 1850. Weil, C. '73. Ueber die Befruchtung und Entwicklung des Kanincheneies. Wiener medicin. Jahrb., Jahrg. 1873. bstr. by W. Miller 72 Hofmann u. Schwalbe’s Jahresberichte, Bd. III. p. 441. Whitman, Charles Otis. '78. Ueber die Embryologie von Clepsine. Zool. Anzeiger, Jahrg. I. No. 1, pp. 5; 6.001 Paly, 2378: : 78°. The Embryology of Clepsine. Quart. Jour. of Mic. Sci., n. ser., No. 71, Vol. XVIII. pp. 215-315, Pl. XII.-XV. July, 1878. Also separate, 101 pp. 4 pl. 1878. "79. Changes Preliminary to Cleavage in the Egg of Clepsme. [Abstract. ] (Aug. 1878.) Proc. Amer. Assoc. Adv. Sci., Vol. XX VII. pp. 263-270. 1879. Pre-print, pp. 263-270. Salem. Feb. 1879. Zeller, Ernst. '76. Weiterer Beitrag zur Kenntniss der Polystomen. Zeitschr. f. wiss. Zool., Bd. XX VII. Heft 2, pp. 238-274, Taf. XVII., XVIII. 23 June, 1876. MUSEUM OF COMPARATIVE ZOOLOGY. INDEX TO AUTHORS Agassiz, A., 447, 516. Agassiz, L., 253, 517. Arndt, 257, 265. Arnold, 270. Auerbach, 254, 259-261, 280, 283-286, 304, 333, 344, 362, 370-372, 399 - 402, 469, 534, 540, 558, 564, 588. Axmann, 256. Baer, Von, 274, 388, 392. Balbiani, 253, 275, 347, 396. Balfour, 254-256, 306-308, 416, 457, 499, 512, 514, 524, 548, 554, 555. Bambeke, Van, 198, 389, 402, 418, 474, 517, 518, 548. Barrois; 425. Beneden, Ed. van, 215, 254, 262, 275, 302-304, 312, 388, 411-415, 417, 473, 516, 549, 567. Beneden, P. J. van, 390. Beneden, Van, et Windischmann, 234 — 236, 390. Benecke. See Kupffer und Benecke. Bischoff, 331, 388, 390, 486, 549. Blanchard, 467, 511. Bobretzky, 313-317, 319, 340, 386, 425, 518. Brandt, 237, 828 — 331, 334, 387, 442, 446. Brooks, 411. Biitschli, 177, 240, 249, 287, 289, 317-324, 349, 393, 395-397, 400, 403, 406, 420, 421, 430-434, 449, 468, 470, 472, 475-477, 5386, 549, 554, 556, 564. 254, 277 — 282, 332, 342-344, Calberla, 455, 496 - 499. _Campana, 479. Carus, 245, 389. Chun, 264. Claparede, 249. Courvoisier, 257. Dallinger and Drysdale, 450. Darwin, 555, 557. Derbés, 245, 392. Dieck, 397, 549. Drysdale, 450. Dujardin, 232. Dumortier, 233, 389-391. 615 CITED IN THE TEXT. Eberth, 258, 344-347, 359. Himer, 250-254, 257, 267, 301. Ewetsky, 342. Flemming, 194, 254, 257, 264, 267, 268, 271, 278, 279, 281, 288, 305, 320, 351, 355-366, 370, 390, 397, 402, 514, 524, 549, 561, 588. Feettinger, 349. Fol, 177, 221, 237, 239-241, 254, 279, 286, 291, 298, 309, 324-327, 390, 396, 397, 402, 406-408, 422, 429, 435, 436, 439, 444-446, 471, 478- 480, 484-486, 488-491, 519, 521, 522, 545, 557, 558, 566 — 590. Frey und Leuckart, 264. Frommann, 257, 261. Galeb, 334, 456. Gegenbaur, 232, 235, 248, 248, 273. Giard, 254, 332, 419, 448, 479, 485, 489, DET: Gibbes, 216. Goette, 298 — 301, 405, 470, 512. Greeff, 253, 419, 424, 478. Grenacher, 253. Grobben, 334, 547. Grube, 245. Haeckel, 288, 393, 410,. 472, 514, 516, 518. Hanstein, 273. Harless, 256. Hatschek, 340, 450, 491, 514. Heitzmann, 258. Helm, 264. Hemsbach, 253, 264. Henneguy, 548. Hensen, 473. Hertwig, O., 177, 198, 248, 253, 254, 292-298, 319, 327, 339, 408-410, 421, 422, 427, 431, 433, 434, 436- 442, 446, 452-455, 464-467, 471, 474, 480-483, 495, 506, 509-511, 514, 518, 519, 529, 536, 540, 541, 545, 548, 550, 553, 569. Hertwig, R., 254, 263, 265, 540. His, 289. Hoek, 549. 616 Hoffmann, 254, 333. Hofmeister, 366, 450, 491. lijima, 535. Jhering, Von, 335, 410, 499. Klebs, 263, 341. Klein, 256, 270. Kleinenberg, 254, 395, 427. Kolliker, 252, 276. Korotneff, 395, 427, 434. Kowalevsky, 249, 276, 301, 516, 517. Krohn, 246, 392. Kupffer, 249, 258, 411. Kupffer und Benecke, 459, 501-508, 518. Lang, 340. Langerhans, 258. Langhans, 265. Lankester, 232, 286, 395, 397. Laurent, J. L. M., 232, 233, 235. Laurent, P., 232. Lavdowsky, 265. Leuckart, 249, 264, 392. Leydig, 216, 252, 264, 275, 390, 547. Lieberkiihn, 256. Loven, 274, 390, 391, 514. Ludwig, 309, 410, 419. McCrady, 329, 487. Mark, 173. Mayer, P., 264, 332, 382, 447. Mayer, S., 258. Mayzel, 244, 341, 348, 349, 859, 558, 559. Meckel von Hemsbach, 2538, 264. Meissner, 246, 248, 273. Metschnikoff, 275, 282. Minot, 486. Miiller, A., 393. Miiller, Friedrich, 390. Miiller, Johannes, 274. Miiller, P. E., 464. Munk, 248. Oellacher, 251-253, 287, 288, 389, 394, 517, 518, 548. Peremeschko, 351. Pérez, 244, 483, 489, 558, 559 — 566. Pfliiger, 251. Priestley, 295, 304, 424. Purkinje, 388. Quatrefages, 246, 392. Rabl, 313, 410, 425-427, 514, 516, 556. BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. Rathke, 553. Ratzel, 276, 393. Ratzel und Warschawsky, 393. Reichert, 246, 250, 392, 517. Remak, 247, Repiachoff, 335, 458. Robin, 197, 390, 416, 473, 564. Russow, 279, 366-368. Sachs, 273. Salensky, 283, 424. Sars, 235. Schenk, 283, 397, 399, 435. Schleicher, 352-355. Schmidt, 232. Schmitz, 380. Schneider, 249, 278, 279, 283, 395. Schultz, 252. Schultze, 252. Schulze, 253, 415, 518. Schwalbe, 257, 262. Selenka, 297, 333, 336-338, 406, 424, 450, 458, 492-494, 499-501, 520. Semper, 252, 255, 342, 411. Spengel, 264. Stecker, 411, 419. Stilling, 256. Stossich, 325, 423, 427-429, 448, 488. Strasburger, 266, 279, 292, 301, 305, 306, 308-311, 344, 348, 350, 363, 370, © 372-385, 411, 419-424, 450-452, 477, 494, 547, 554, 556, 564, 589. Stricker, 268 — 270. Torok, 266. Treub, 385 — 387. Trinchese, 254, 255, 262. Tschistiakoff, 368-370, 380. Turpin, 232. Van Bambeke. See Bambeke. Van Beneden. See Beneden. Villot, 387, 397. Vogt, 253, 261. Von Baer. See Baer. Wagener, 256. Walter, 249. Warneck, 177, 220, 234-2438, 274, 330. Warschawsky, 393. Weil, 468. Whitman, 197, 247, 254, 282, 301, 338, 411, 421, "422, 460 - "464, "487, 503 — 509, 513, 516, 518, 524, 535, 547, 556, 557. . Windischmann, 234 — 236, 390. Zeller, 311, 424. EXPLANATION OF FIGURES. 618 BULLETIN OF THE LETTERS. THE following letters are used throughout to designate respectively : — A. A = Amphiaster. Pv = Purkinjean vesicle. Al = First archiamphiaster. pz = Clear zone in the yolk. A? = Second archiamphiaster. 4 = Amphiaster of first segmenta- | R. r = Polar globule (Richtungs- tion sphere. blaschen). @ == Aster. rv! = First polar globule. aa == Central area of aster. r/’ == Second polar globule. aa’ = Structures at the centre of aa. rv == Nuclear structure of r. ae == External aster. rnt = Nucleolar structure of r. ai = Internal aster. ar = Rays of aster. S. sp- = Nuclear spindle. ar! =$Thickenings in ar. sp! ==: First maturation spindle. ars = Spiral aster-rays. sp» == Second maturation spindle. sp? = Spindle of first segmentation F. fpn = Female pronucleus, sphere. Jpnl = Female pronucleolus. spf = Spindle fibres. spf! == Interzonal filaments. M. ma = Male aster. spf!!/= Thickenings in spf! (Zell- mpn = Male pronucleus. platte 7). mpnl == Male pronucleolus. spl == Lateral zones of spindle thickenings. N. 2 = Nucleus. spm = Median (equatorial) zone of spindle thickenings. Pp = Pedicel, or neck of polar spz == Spermatozoa. globule. pn, pn! = Pronuclei. Vi. V,, = Vitellas. pnt = Pronucleoli. ve == Vitelline envelope. pp = Pedicel-plate (Zellplatte ?). vm = Vitelline membrane. TREATMENT, ETC. All Figures, except 62%, 94, and 95, were drawn with the aid of the Chevalier- Oberhauser camera; and all, except 80°, 80°, and 95, relate to Limax campestris. Figures 1-21, 27, 49, 51, 62%, 65, 70°, are magnified 140 diameters; Figs. 30- 38, 76, about 200 diameters; Fig. 95, 300 diameters; all other Figures 750 diameters. The following Figures were made from living eggs: 1-21, 27, 30-38, 49, 51, 62°, 65, 70*, and 95. Figures 28, 29, 44, 52, and 52%, are from sections of eggs hardened in chromic acid ; all others, except Figs. 26 and 76, from the egg entire. Osmic acid (1%), followed by carmine, was employed to harden and stain those from which Figs. 63, 64, 68-70, 71, 72, 75, and 77, were drawn. Those of Figs. 69 and 75 remained unstained by Beale’s carmine. All eggs not otherwise specified were treated with acetic acid (1%-2%) for three hours or more, and were subsequently stained in Beale’s carmine. . MUSEUM OF COMPARATIVE ZOOLOGY. 619 PLATE I. Figs. 1-20. Formation of polar globules. Figs. 1-9. Successive views of the same egg at 6:00, 6:02, 6:04, 6:06, 6:30, 7:40, 9:30, 10:45, and 11 o’clock. Figs. 10-14. Formation of second polar globule. Another egg seen at 11:08, 11:09, 11:10, 11:12, and 11:15 o'clock. Figs. 15-20. Formation of second polar globule as seen in another egg, at 6: 08, 6:33, 7:04, 7:05, 7:06, and 7:15. First segmentation of this egg nearly completed at 10:00 o’clock. Fig. 21. Egg showing an irregular zone of clear protoplasm and two pronuclei. Fig. 22. The deeper of the lateral zones of fibre thickenings has reached the border of the well-defined central area of the internal aster. Optical meridional section. Fig. 23. Optical section in the plane of the polar globule, showing the second archiamphiaster ; the peripheral aster more sharply outlined than the deeper one. Fig. 24. Same seen along the axis of the spindle. Focused a little above the centre of the superficial aster ; the polar globule ‘‘ projected.” (Its outline has been made too irregular and ragged in lithographing. ) Fig. 25. Another egg of about the same stage, and seen in the same position as Fig. 22. Fig. 26. Yolk elements from the vitellus of a crushed egg. Fig. 27. Peculiar appearance, as of decussating fibres, seen at the animal pole after the formation of the first polar globule. Figs. 28, 29. The fourth and third respectively of five successive sections of the egg, Fig. 21, put in acid during the first segmentation. Slightly distorted by the traction of the knife in cutting. The plane of section is not quite parallel with the plane determined by the polar axis and the line joining the centres of the two asters, but cuts both these lines. From its obliquity to the polar axis, it results that the polar globules, and the curved remnant of the spindle (interzonal filaments), which both lie in this axis, are found not in the same but in successive sections. From its obliquity to the line joining the astral centres, it results that the nucleus of one of the two segmentation spheres is cut, as shown in Fig. 29, while the other remains untouched, and also that the interzonal filaments (spf’’) are cut across in the sphere “marked ‘‘y” (Fig. 29). Chromic acid preparation. Figs. 30-32. Three successive views of an egg, at 8, 8:54, and 9 o’clock. Fig. 30. Polar globules already formed. The two pronuclei with very clear cir- cular outlines of nearly equal size. No change from the spherical form observed. Fig. 31. The egg has changed form slightly, and two oval, ill-defined spots are visible, at some distance apart, the pronuclei having disappeared. The yolk shows a faintly expressed radial arrangement of granules about these two spots. Fig. 32. The spots are farther apart; the radiate arrangement more distinct ; the cleavage furrow at the animal pole of the yolk is quite pronounced. Figs. 33-385. Three views of an egg, at 7:54, 8:35, and 9:12 o'clock. Fig. 33. A clear spot at the animal pole, and deeply penetrating narrow zone of clear protoplasm (pz) near the equator. 620 BULLETIN OF THE Fig. 34. The clear spot has moved to near the centre of the egg; the equatorial zone is less distinct. Fig. 35. The first segmentation furrow has already extended to the vegetative pole. . Figs. 36-38. Three views of the same egg, at 8:10, 9:04, and 9:15 o'clock. Fig. 36. Male and female pronuclei, and equatorial clear zone (pz) visible, the latter intermediate in prominence between that of Figs. 33 and 34. Fig. 37. Beginning of the first segmentation of the yolk. The pronuclear struc- tures have disappeared, and the oval spots, from the position of the egg, partly cover each other. Fig. 38. Near the close of the first segmentation. PLATE II. Fig. 39. Optical section of an egg, showing the first archiamphiaster, and pe- ripheral clear areas in the yolk. Fig. 40. Optical section of an egg and first polar globule, with lateral zones of thickenings, prominent interzonal filaments, and possible indications of an ameboid character of the yolk at the animal pole. Fig. 41. Surface view of the polar globule of the same. Fig. 42. View of same globule, the optical axis coinciding with the primary (ani- mal) radius of the egg. It shows the annular arrangement of the spindle thicken- ings, and the outline of the pedicel. Fig. 43. First archiamphiaster. The external aster causes a protuberance at the surface of the yolk, and exhibits a highly refractive body at the centre of radiation. Nuclear spindle inconspicuous ; equatorial thickenings not prominent. Fig. 44. Section of an egg just before the first segmentation. The plane of sec- tion is parallel with the axis of the spindle. About one third of the spindle was cut away by the section preceding the one here represented. A highly refractive spherical body occupies the centre of each of the astral areas, and the thickenings of the spindle fibres are arranged in two closely approximated parallel zones. ! Fig. 45. First ‘archiamphiaster at the time the rays of the external aster attain the surface of the yolk. The external aster is more sharply outlined than the in- ternal. The first maturation spindle presents only a single (equatorial) zone of fibre thickenings. The flattened appearance of the animal pole is probably due to the resting of the yolk on that pole during its preparation, and while still incompletely hardened. Fig. 46. Equatorial optical section of the same; the spindle thickenings are projected, and exhibit the usual annular arrangement. Fig. 47. External aster of same; the optical axis coinciding with the axis of the spindle. The rays have a spiral course. Fig. 48. The first archiamphiaster has approached the animal pole still more closely than in Fig. 43. The external aster has thereby become more conspicuously unsymmetrical. The spindle is more distinctly marked, and shows the equatorial zone just dividing into its lateral halves. Both asters exhibit large areal corpus- cles. The “halos” around each should be narrower ; more as in Fig. 43. Fig. 49. Living egg at the close of the formation of the first polar globule. Radi- MUSEUM OF COMPARATIVE ZOOLOGY. 621 ate markings at the clear animal pole of the yolk. Numerous highly refractive spermatozoa in the vicinity of the vitellus. Fig. 50. First archiamphiaster has migrated still farther than in Fig. 48 toward the animal pole, the centre of the external aster having nearly attained the surface of the yolk. The conical protuberance caused by ae is covered by a cap of finely granular substance (compare text, p. 198). Lateral zones of spindle thickenings half-way between the equator and the poles of the spindle. Fig. 51. A single ill-defined clear spot seen in the living egg, where the pronuclei are found in the ‘same egg hardened and cut (Figs. 52, 52"). Equatorial zone of clear protoplasm, pz. Figs. 52, 52%. The third and fourth of five sections through the egg, shown in Fig. 51, the egg having been put in chromic acid immediately after the outlines (Fig. 51) were made. Both pronuclei contain numerous.nucleolar bodies joined by irregular fibres, which thus produce an indistinct reticulum. In Fig. 52 are to be seen the two polar globules, nearly the whole of the female pronucleus, a portion of the male pronucleus, and, near the border of the latter, an incipient aster of 4%, with a conspicuous highly refractive structure (aa’) occupying the centre of the astral area. In Fig. 52° is seen the remainder of the male pronucleus. No other aster had as yet made its appearance in the yolk. PLATE III. Fig. 53. Archiamphiaster, whether the first or the second is uncertain. Con- sult text at pp. 189, 206. Fig. 54. Another view of the same. The optical axis coincides with the axis of the incipient spindle. The nuclear substance, largely accumulated on one side of the spindle, is seen as though ‘‘ projected” on the equatorial plane passing through the centre of the internal (deeper) aster. Fig. 55. Second archiamphiaster. The spindle exceptionally slender. The yolk about the animal pole is constricted by two or three rings, which give it a wavy out- line when seen in optical section. Compare with the description of the formation of polar globules in Clepsine, as given by Whitman (78%, pp. 232, 233, and separate, pp. 18, 19, Pl. XII. Figs. 2-6). Fig. 56. Equatorial optical section of same. The external aster with spiral rays projected ; optical axis slightly inclined from the spindle axis. Fig. 57. Internal aster of the second archiamphiaster, with compound curvature of rays. Male and female pronuclei; the centre of the aster nearer the latter. ‘*Interzonal filaments,” exceptionally prominent, unite the second polar globule to the vitellus. A thin pellicle (vitelline membrane ?) stretches over the second polar globule, the first having become detached. Granulations of the yolk omitted. Fig. 58. Male and female pronuclei, the latter near, but not coinciding with, the centre of the inner aster of the second archiamphiaster. In this figure only that por- tion of the inner aster is shown which lies very near the surface of the yolk, the rays of which are stout and nearly straight. The centre of the astral areais occupied by a few granules not quite so conspicuous as the pronucleoli, and certainly not embraced within the outline of the female pronucleus, which is well marked. Compare Fig. 78 or deeper portions of this aster. 622 BULLETIN OF THE Fig. 59. Yolk of exceptional form. The primitive axis lies in the plane of the optical section. The pronuclei, male and female, have attained considerable size, the latter still united to the polar globule by interzonal filaments. About midway between the pronuclei a dense, but less granular area, around which the yolk granules show a radial arrangement, —the senescent internal aster of the second archiamphiaster. The region of this aster is more deeply stained than the surrounding yolk. Another region of crescentic form appears in the vegetative half of the yolk beyond the male pronucleus, and is likewise deeply stained. It is represented in the figure by deeper shading. Fig. 60. Optical section oblique to the primitive axis. Polar globule ‘“‘pro- jected.” Male and female pronuclei, the latter distinct -from the central area of the internal half of the second archiamphiaster. Fig. 61. Equatorial optical section. Polar globules, pedicel, lateral zone of thick- enings, granules of astral area, and short stout rays of aster, projected. Granulation of the yolk omitted. A sufficient difference in the prominence of the long and the short rays has not been observed in lithographing. Fig. 62. Meridional optical section of same, the first polar globule being omitted. Lateral zone and areal corpuscles more nearly approximated than usual. Fig. 62°. Living egg near the close of the first segmentation. Consult the text at p. 223. Fig. 68. Female pronucleus small, homogeneous, lying at the border of the cen- tral area of the internal aster. The ‘‘interzonal filaments” exhibit a plate, pp (the Zellplatte ?), near the point of their deepest constriction. The areal corpuscle of the external aster fused with the envelope of the polar globule at its distal pole. Osmic acid preparation. Fig. 64. The second polar globule of the same egg seen from the animal pole. Osmic acid preparation. Fig. 65. The male and female pronuclei in the living egg. Fig. 66. Formation of the second polar globule; ‘‘interzonal filaments” bent nearly at right angles (compare Fig. 19) ; the spiral rays of the internal aster radiate from a spiral line, a8; the areal corpuscles and the thickenings of the internal zone not distinguishable from each other ; two vesicular structures in the vegetative hemi- sphere — incipient male pronuclei (?) —do not contain nucleolar corpuscles. Fig. 67. Portion of the same egg seen after rotating the yolk 90° about the primitive diameter as an axis. The internal end of the spindle is deeply stained, but not sharply defined. PLATE IV. Fig. 68. Second polar globule with nucleus, and longitudinal folds in the en- velope of its pedicel. The position of the vitelline half of the “interzonal filaments ” ig indicated by a streak of non-granular protoplasm extending to the female pro- nucleus, in which, however, filaments are not traceable. Both pronuclei pear-shaped, with the sharper ends (not outlined with sufficient distinctness) directed toward the centre of a clear spot which is surrounded by numerous faint rays, —the senescent internal aster of the second archiamphiaster. The pronucleoli more numerous in the female (25) than in the male (20) pronucleus. Osmic acid preparation. Fig. 69. Oblique view of the formative pole of the yolk (the two polar globules ' MUSEUM OF COMPARATIVE ZOOLOGY. 623 omitted), showing male and female pronuclei, in which no nucleolar structures are discernible. An invagination of the yolk into one side of the female pronucleus is compensated by an evagination of the wall of the latter into the substance of the male pronucleus. Compare Fig. 75. Osmic acid preparation. Fig. 70. Pronuclei. The position of the internal aster of 4? is indicated by the irregular non-granular area near the female pronucleus, but no radial differentiation can be distinguished. The pronucleoli of about the same number (15 and 16) in each of the pronuclei. Osmic acid preparation. Compare Fig. 72. Fig. 70%. Living egg. Recession of the granular yolk from the surface, especially at the primary'pole, which lies a little to the left of the polar globules. Fig. 70°. Early stages in the formation of the pronuclei: a, the female pro- nucleus; 8, the male. Fig. 71. Second polar globule of the egg shown in Fig. 72 with two nuclear structures, as seen after rotation about the primitive diameter as an axis. Osmic acid preparation. Fig. 72. Meridional optical section. The pronuclei large, considering the dis- tance between them. The centre of the senescent internal aster of 4? nearly coin- cident with the centre of the female pronucleus, ‘as shown by the course of the faint rays still traceable. Osmic acid preparation. See also Fig. 70. Fig. 73. Pronuclei still unconsolidated after the appearance of one of the asters of the amphiaster of the first segmentation sphere. Nucleoli numerous. No trace of the complementary half of this amphiaster discoverable. Compare Fig. 80. Fig. 74. Both asters of A? extensively developed ; one distant from the female pronucleus, which still remains unfused with the male pronucleus, although in con- tact with it. Fig. 75. A deep cup-shaped invagination of the yolk has forced inward one side of the female pronucleus, and a slight projection from the opposite side of the latter is plunged into the male pronucleus. Both present a wrinkled appearance, but no trace of nucleolar structures. Osmic acid preparation. Compare Fig. 69. Fig. 76. -Yolk crushed after the formation of the amphiaster of the first segmen- tation sphere. The spindle is proportionately somewhat shorter than before the yolk was crushed. Slender strings of protoplasm stretch from the spindle to one of the fragments of an aster. Fig. 77. The two pronuclei near the primary pole, each containing about a dozen nucleoli. Those of pn/ are shaded to distinguish them from those of yn. No trace of either aster. Osmic acid preparation. Fig. 78. Equatorial optical section of the egg shown in Fig. 58. The outlines of the polar globule and of the two pronuclei ‘‘ projected.”’ The superficial rays and the granulations of the yolk are omitted, so as to show better the spiral course of the numerous deep rays. Seen from the primary (animal) pole. Consult text, p. 209. Fig. 79. Pronuclei seen from the primary pole, each containing about thirty pronucleoli. Only one aster of 4? discernible. Pronuclei not confluent. Fig. 80. The ege which is exhibited in Fig. 73, so rotated that the face of the pronucleus nearest the aster appears in profile. The centre of the aster lies at some distance from the sharp outline of the pronucleus. Fig. 80% Egg near the close of the second segmentation. The outlines of two of the blastomeres, and partial outlines of the other pair, as seen from the secondary 624 BULLETIN OF THE pole. Compare the shape of the nuclei, and the relation to their respective asters, with that of the pronuclei in Fig. 68. The more pointed ends of the nuclei are directed obliquely away from the observer, and the interzonal filaments, which are much thicker in the middle than toward the ends, are so bent as to present to the observer their convexities. Fig. 80°. Nearly meridional view of the “ primary” half of an egg from an undetermined species of Limax. Each pronucleus contains a single nucleolar struc- ture which greatly exceeds any of the others in size; it is indicated by its shad- ing, the remaining nucleolar bodies being only outlined. Fig. 80°. The second polar globule of the same egg as that last figured, seen in profile, to show the relation of the vitelline membrane, detached by the hardening reagent, and the interzonal filaments to both polar globule and yolk. Fig. 81. Vitellus showing one extensive aster with a homogeneous centre (female pronucleus ?), the rays of which are numerous and slender, and several other less extensive asters with few stout rays. The latter are probably induced by the pene- tration of a corresponding number of spermatozoa into the yolk. Abnormal condition. PLATE: V. Fig. 82. Third amphiaster (43) after the almost complete disappearance of the pronuclei. A few exceedingly faint outlines (pni?) may possibly be traces of pro- nucleoli. An irregular plane of prominent granules (incipient nuclear plate ?) sepa- rates the halves of the amphiaster. Asters flattened in the direction of the axis of the still incomplete spindle. Thickenings (a7’) occur near the central ends of many of the rays. The central areas contain numerous prominent granules (aa’). Compare with Fig. 85. Fig. 83. Amphiaster of the first segmentation sphere, with very prominent spindle and equatorial zone of fibre thickenings (spm), the latter shown in Fig. 84, as they appear when the optical axis corresponds with the axis of the spindle. Fig. 85. View from the secondary (vegetative) pole. The asters of A® well developed before the complete union of the pronuclei. A few highly refractive granules near the axis of the future spindle (too prominent in the engraving). One of the astral areas is homogeneous, the other contains granules. The rays of the asters present thickenings forming a zone concentric with the area. The external limits of the thickenings are not sufficiently defined. The zones, interrupted two or three times by the absence of thickenings from several neighboring rays, are not quite accurately reproduced. Fig. 86. A nearly face view of the amphiaster of the first segmentation sphere. A remnant of the substance of the pronuclei is still visible between the spindle and the animal pole. : Fig. 87. The egg shown in Fig. 86, seen lengthwise of the spindle. The re- mains of the nucleus are more distinct than in the preceding view. No fibre thick- enings (nuclear plate) observed. Compare also Figs. 88 and 89. Fig. 88. A slightly more advanced stage than is shown in Figs. 86, 87. The asters nearly cover each other, the line of vision being almost parallel with the spindle axis. The remnant of the nucleus, still sharply outlined, lies near the animal pole, and is surrounded with a narrow zone of non-granular protoplasm. MUSEUM OF COMPARATIVE ZOOLOGY. 625 Fig. 89. The same egg as the last, rotated nearly 90° about its primitive axis. The remnant of the nucleus appears less sharply outlined. The elements of the equatorial nuclear plate are very evenly arranged, and conspicuous. Fig. 90. A slight furrow introducing the first segmentation of the yolk has made its appearance at the animal pole. A vitelline membrane is detached from the yolk over a space corresponding to this furrow. The nuclear spindle is viewed somewhat obliquely, so that the lateral disks of fibre thickenings are not seen exactly edgewise, and therefore appear oval. The left-hand edge is represented in the lithograph as farthest from the observer ; the right-hand edge of the oval should have been made the fainter, as it is really the more remote. Fig. 91. Constriction further advanced than in Fig. 93; nuclei much larger ; interzonal filaments distinguishable only near the plane of division between the two secondary cells. Asters becoming less distinct. Fig. 92. Equatorial thickenings in the spindle of the first segmentation sphere, as seen when the spindle is viewed lengthwise. Fig. 93. Formation of the nuclei of the first pair of blastomeres. Interzonal fila- ments sharply bent and slightly thickened. Compare Fig. 29. Fig. 94. Spermatozoon with vibratile (?) membrane. The tail end should have been made thinner. The free edge of the membrane indicated by the sinuous line. Fig. 95. View of a portion of a living egg of Limax sp.? toward the end of the formation of the second polar globule, to show the existence of pseudopodia. — —t 0 Mus.Comp.Zoél\ ull ? @] t 1 e E.L.Mark,d oS AEN ance ae 1, VL 0 al\ Bull.Mus.Comp.Z06 L.Markdel. E Limax. Figs: 39 3520.F il e A Meisel, lith F Bull.Mus.Comp.Zo61 Vol. VI. PINS 4 Peano iey Sp Ee E.L.Mark del { ie iS { \ CALE a we, ¥ o5 oc oe a £ pects — =z Figs. 53-67, FLA. Limax. +] Meisel, lith A Bull.Mus.Comp.Zool Vol. VI. cee cee igs. 68-81, Pl WW, Bull.Mus.Comp.Zodl Vol. VI. E.L.Mark del 2s S25 ¢ “. ¥ SCAR ARE we hs APR B® O57 QL Harvard University. 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