PART 6 A MONOGRAPH OF THE EXISTING CRINOIDS 817 



is in tlie form of a high rounded dome, beginning to curve inward at about the fifth 

 brachial; from this point the ambulacra, which reach the arms at about the ninth 

 brachial, are supported upon high narrow bridges as in Gephyrocrimis, Thalassocrinus 

 and Plilocrinus. Up to the level of the general surface of the disk, the pinnules are 

 connected with it by webs or thin sheets of perisome, resembling the thicker sheets 

 which support the brachial aml^ulacra in their passage to the arms. A strip of thickened 

 perisome extends downward intcrradially to the union of the first brachials, just above 

 which it bears a cluster of about a dozen rounded calcareous plates. Just above the 

 union of the first brachials are deep oval pits, whether blind or not cannot be determined 

 without dissection; similar, but somewhat larger pits occur just beyond the distal 

 angles of each first brachial, on either side of each syzygy, and at the base of each 

 pinnule. 



Locality.— Siboga station 177; north of Ceram Qat. 2°24'30" S., long. 129°- 

 38'30" E.); 1633 meters (during the haul the depth diminished to 1300 meters); dead 

 coral and stones, covered with manganese; September 1, 1899 [A. H. Clark, 1912, 

 1918; Gislen, 1924] (1, Amsterdam Mus.). 



Remarks [by A.M. C.]. — In 1928 Gislen tentatively put forward the suggestion that 

 Pentametrocrinus varians might belong to the genus Atopocrinus since both have 

 pinnules on the proximal brachials unlike the other species of Pentametrocrinus. How- 

 ever, as he pointed out, there are no visible basals in P. varians and the centrodorsal 

 and cirrus sockets are quite difTerent. Also the proximal brachials of varians are 

 oblong rather than triangular and the segments of the proximal pinnules are very 

 much shorter, besides being modified into a crest near the base of each pinnule. Though 

 varians does stand apart from the other species of Pentametrocrinus, there is no doubt 

 in my mind that it is much more nearly related to them than to Atopocrinus. 



Genus ATELECRINUS P. H. Carpenter 



Antedon (part) PouRT.iLiis, Bull. Mus. Comp. Zool., vol. 1, No. 11, 1869, p. 356; vol. 5, No. 9, 1878, 

 p. 214. 



Atelccrinus P. H. Carpenter, Bull. Mus. Comp. Zool., vol. 9, No. 4, 1881, p. 152 (met with at Blake 

 stas. 150, 151, 222), p. 161 (saccuU present), p. 166 (characters; 2 species mentioned, cubensia 

 [Antedon cubensis Pourtalfes, part] and balanoides) ; Journ. Linn. Soc. (Zool.), vol. 16, 1882, p. 

 488; Rep. British Assoc, for 1881, 1882, p. 672; Proc. Roy. Soc, vol. 35, 1883, No. 225, p. 139 

 (comparison with Thaumalocrinus) . — Perkier, Compt. Rend. Acad. Sci., vol. 96, No. 11, 1883, 

 p. 725.— P. 11. Carpe.ntek, Phil. Trans. Roy. Soc. for 1883, pt. 3, 1884, p. 920 (basals compared 

 with those of Thaumalocrinus), p. 920 (referred to the Comatulidae). — Lockincton, Standard 

 natural history, vol. 1, 1884, p. 142. — P. H. Carpenter, Challenger Reports, Narrative, vol. 

 1, pt. 1, 1885, p. 311. — Perrier, M^moire sur I'organisation et le dcveloppement de la coraatule 

 de la M^diterranfie, 1886, p. 106 (sacculi). — P. H. Carpenter, Quart. Journ. Micr. Sci., new 

 ser., vol. 27, 1887, p. 385 (sacculi present); Challenger Reports, Zoology, vol. 26, pt. 60, 1888, 

 p. 68 (detailed discussion). — A. Agassiz, Bull. Mus. Comp. Zool., vol. 15 (reprinted as "Three 

 Cruises of the Blake," vol. 2), 1888, p. 124. — Rolleston and Jackson, Forms of animal Ufe, 

 1888, p. 570. — DE LoRiOL, Paleontologie frangaise, ser. 1, Animaux invertdbrds, terrain juras- 

 sique, vol. 11, pt. 2, 1889, p. 434. — Bather, Ann. Mag. Nat. Hist., ser. 6, vol. 7, 1891, p. 464 

 (listed). — P. H. Carpenter, Journ. Linn. Soc. (Zool.), vol. 24, 1891, p. 59 (comparison of calyx 

 with that of an immature Poliomelra prolixa). — Norman, Ann. Mag. Nat. Hist., ser. 6, vol. 

 8, 1891, No. 44, p. 181. — A. Aoassiz, Mem. Mus. Comp. Zool., vol. 17, No. 2, 1892, p. 27 (pin- 

 nulation). — Perrier, Trait! de Zoologie, 1893, p. 858. — Lang, A text book of Comparative 

 Anatomy, vol. 2, 1896, p. 313. — Bather, Royal natural history, vol. 6, 1896, p. 300; Rep. British 



