No. 8. — Notice of some Crinoids in the collection of the Museum 

 of Comparative Zoology. By Austin Hobart Clark. 



Two species of Crinoids were met with during the cruise of the 

 " Albatross " in the eastern Pacific, one near the Central American 

 coast, and the other approximately midway between the Marquesas 

 Islands and Central America. The former, an unstalked form belonging 

 to Heliometra, is represented by four specimens from three stations; the 

 latter, a species of Bathycrinus, is represented by a single specimen 

 without arms. The Bathycrinus, however, is a species of consider- 

 able interest, for not only does it greatly extend the range of the genus, 

 which was hitherto known in the Pacific only from Kamchatka and 

 southern Japan, but it presents a most extraordinary superficial resem- 

 blance to Rhizocrinus in certain of the characters of the stem and basals ; 

 so close, in fact, that the specimen was first recorded (Mem. Mus. Comp. 

 Zool, 1906, 33, p. 49) under that generic name, and a close examination 

 under a microscope is necessary to reveal its true affinities. 



Of the new species here described, Heliometra juvenalis calls for 

 special mention. While undoubtedly closely allied to H. esclirichtii, 

 it is remarkable in having prominent basals, cirri with less than twenty 

 segments, and very short and stout lower pinnules, which are, in fact, 

 much the shortest on the arms. The enlarged ovaries, however, con- 

 taining ova, show that the specimens are adult, although the structure 

 is that of very young specimens of other species of the genus. While 

 no positive statement can be made on only two specimens, this seems to 

 be a case of arrested development at a very early stage. Whether it is 

 a permanent character or not must be left for future investigation ; 

 nothing similar is recorded, nor have I met with a similar case in my 

 studies on the group. 



STALKED CRINOIDS. 

 Bathycrinus equatorialis, sp. nov. 



Radials and arms lacking. 



Basals closely united into a smooth ring, slightly wider above than below, about 

 as high as its greatest diameter ; the sides of the ring are markedly convex, a 

 character not known in any other species of Bathycrinus. 



