80 NATUKAL HISTORY BULLETIN 



similar but smaller plates, each of wMch abuts against two adam- 

 bulacrals. 



The two primary interradial rows start from an impaired 

 plate, in line with the suture between the first marginals. Its 

 two halves diverge rapidly, in a curve, leaving a small, nearly 

 smooth and naked, triangular area outside the jaw-plates. A 

 few irregular small plates are here concealed under the dermis. 

 In the type two to three of the interactinal plates bear a single 

 small blunt central spine, none have spinules. 



The adambulacral plates are concealed by the dermis, which 

 continues upward on the bases of the outer row of spines and 

 forms a short continuous web between them. 



Each adambulacral plate bears an inner small furrow-spine, 

 and on the proximal part of the groove, mostly two larger, a lit- 

 tle thicker, and somewhat flattened, oblong or slightly clavate 

 blunt spines. Where not too crowded, these stand side by side, 

 but they often stand more or less obliquely, and there may be 

 but one on some plates. Near the distal end of the groove, they 

 become more slender and more oblique, due to crowding. Near 

 the jaw-plates a few plates may have two inner spines. 



The adoral and peroral spines of the jaws are similar to those 

 of the adambulacral plates, but slightly stouter, especially the 

 apical ones. West Indies, special locality not known. ( Coll. A. 

 E. Yerrill). Also taken by the Albatross. 



This is probably immature, but I am unable to refer it to any 

 described species. 



Suborder Yelata Perrier. (See above). 



Family Pterasterid.^] Perrier. 



PterasteridcB Perrier, op. cit., 1875; op. cit., 1884; op. cit. p. 180, 1894. Ver- 



rill, op. cit., 1899. 

 Pterasteridce (pars) Sladen, Yoy. Challenger, vol. xxx, p. 468, 1889. 

 PterasteridcB Fisher, op. cit., 1911b, p. 343 Verrill, op. cit., 1914a, p. 266. 



This is one of the most peculiar groups of starfishes hitherto 

 discovered. It shows in general characters, a remarkably high 

 degree of specialization not found in any other group. Most of 

 the genera and species are from the deep sea. 



Disk usually plump ; rays 5-8, usually five, rarerly 6-9 ; upper 



