244 



THE VOYAGE OF H.M.S. CHALLENGER. 



2435 fathoms; Globigerina ooze; Itnttom temperature 3G°'5 F. One nearly complete 

 specimen, and one stem with the basal ring attached, but wanting the rest of the calyx. 



Remarks. — The shortness of the arms 

 and the absence of well grooved pinnules 

 indicate that the single specimen of this 

 elegant little species is not fully developed. 

 Sir Wpalle Thomson' said that " there is no 

 trace of pinnules, and the arms resemble in 

 character the pinnules of Rhizocrinvs." 

 There are, however, little .stumps on the 

 terminal joints of one or two of the arms 

 which give them the appearance of bifurca- 

 tion, just as at the growing point of the 

 arms of a young Comatula or Pentacrinns; 

 and I see no reason to doulit that these 

 stumps are the commencing pinnules. 



T have already pointed out that the arm- 

 ioints of Bathi/cri)uis gmcili.'! are united in 

 pairs exactly like those oi Bathi/crinus aJdri- 

 chianus and Rhizocrimis, excej^t that in the 

 latter genus the union is a syzygial one ; and 

 the supposed resemblance of the arms of 

 Batliijc rinus gracilis to the pinnules of Rhizo- 

 crimis thus disappears. 



As might be expected from its geogTa- 

 phical position, Bathi/crimis grcwilis comes 

 nearer to Bathycrinus carpcnteri than to 

 either of the Challenger species. The lower 

 stem-joints are strongly constricted with 

 markedly expanded ends as in that type ; 1 >ut 

 the absence of orals, the well defined medio- 

 dorsal keel on the radials and arm-bases, and 

 the serrate condition of the arms are sufficient 

 to distinguish it without difficulty. 



During the expedition of the " Talisman " 

 in 1883 ■■ a few much mutilated specimens 

 both of Bathycrinus gracilis ViiiA of Rhizocrinus raivsoni {Democri mis jxii fait i, Perrier) 



' The Depths of the Sea, p. 452, 1873. 



" Comptes reiidus, t. xcvii. p. 1392. See also H. Filhol, Voyage du " Talisman " in La Xafurc, No. 572, 17th Jlay 

 1884, p. 391. 



Fig. 16. — Lalhycrinas gracilis, WyviWe Tbomsoa ; twice 

 the natural size. 



