250 ECIIINODERMA OF THE INDIAN MuSEUM, PART VII. 



learned, however, the appHeation of a specific name tn tliis fragment couhl only 

 cause confusion. 



Placed side by side with the arms of Dccamctrocriwus rugosiis from the 

 Hawaiian Islands no differences, except the proportionately greater size and 

 the somewhat different arrangement of the syzygies. were detected. 



The Pentametrocrinida? are peculiar among the comatulids in having un- 

 divided arms of very primitive structure, morphologically entirely different 

 from the undivided arms of the species of the genus Eudiocrinus, which belongs 

 to the Zygometridfe. This single arm, however, divides twice. The thirty-fourth 

 brachial from the proximal end (as preserved) is the hypozj'gal of a syzygial pair , 

 the epizygal of this syzygial pair has its distal face divided, and bears two 

 brachials, both of which are but slightly smaller than the more normal one would 

 liave been ; the first brachial beyond this axillary on the left (viewed dorsally) 

 side is short, and is united by syzygy to the succeeding ; on the right the first 

 brachial is twice as long, obliquely wedge-shaped (the longer side inward); the 

 two are interiorly united basally for about four-fifths of tlie length of the left 

 (smaller and shorter) brachial. The tvventy-fiftli brachial further on bears a well 

 developed arm as large as the main trunk instead of the usual pinnule. In this 

 supernumerary arm the fourth and fifth brachials are united by syzygy as in 

 primary arms. 



Genus PENTAMETROCRINUS. 



Thmimntnrrrmis 18S4. P. H. Carpenter, Phil. Trans. Roy. Soc, 1S83, p. 919 

 (Thaumatocrinus renovatus, sp. nov., a young specimen not identifiable 

 with certainty). 



Pentametrocrinus 1908. A. H. Clark, Proc. Biol. Soc. Washington, vol. 21, 

 p. 134 (Eudiocrinus japonicus P. H. Carpenter, 18S2). 



PENTAMETROCRINUS TUBERCULATUS. 



Eudiocrinus tuberculatns 1907. A. H, Clark, Proc. U. S. Nat. Mus., vol. 32, 



p. 573. 

 Pentametrocrinufs tnherculatus IOCS. A. H. Clark, Proc. Biol. Soc. Washington, 



vol. 21. p. 135. 



Habitat. — Southern Japan. 



Depth. — 169 fathoms. 



PENTAMETROCRINUS DIOMEDE/E. 



Peritametrocrinns diomedem 1908. A. H. Clark, Smiths. Miscell. Coll. (Quarterly 

 Issue), vol. 52, part 2, p. 2.'U. 



H.vEiTAT. — Philippine Islands, and northward to southern Japan. 

 Depth.— 103-152 fathoms. 



