82 NATURAL HISTORY BULLETIN 



Subfamily Hymenasterin^e. 



The genera Hymenaster, Cryptaster and their allies form a 

 distinct subfamily, Hymenast&rince, differing from PterasterincE 

 in lacking webbed combs of adambulacral spines and in other 

 characters. It is a characteristic deep-sea group. One or two 

 species occur in the West Indies in deep water. 



Subfamily Pterasterin^. (See above). 



Genus Pteraster M. and Trosch. 



Fteraster Miiller and Troschel, Syst. Aster., p. 128, 1842. Type, P. militaris. 

 Sladen, op. cit., p. 470, 1889. Fislier, op. cit., 1911Z), p. 344, (Analy- 

 tical table of all kno^vn species, pp. 368-370.) Perrier, op. cit., 1894, 

 p. 181. Clark, op. cit., 1908, p. 286 (Analytical Table.) Verrill, op. 

 cit., 1914a, p. 267. 



Hexaster Perrier, Comptes-rendus, vol. 112, p. 1227, 1891. Type. H. ohscurus 

 Perrier. 



Temnaster VerriU, Proc. U. S. Nat. Mus., vol. 17, p. 275, 1894. Type T. 

 hexactis V. = H. ohscums P. 



Disk large ; rays 5 to 8 ; ambulacral grooves turn up distally, 

 more or less reaching to the upper side of the rays. 



Adambulacral spines foi-m large, webbed combs. Retroambu- 

 lacral or ''actinomarginal" spines are closely appressed, ending 

 in a fringe or fold. One pair of specialized epioral spines; 

 these are often translucent distally. Supradorsal membrane 

 furnished with a central contractile osculum, guarded by five or 

 more groups of webbed, projecting spines. It usually contains 

 irregular muscular or elastic fibers for its support and sometimes 

 calcareous deposits. The muscular bands usually do not form a 

 regular network and are generally very inconspicuous externally. 

 Usually two rows of ambulacral sucker-feet. 



Pteraster caribb^us Perrier. 



Pteraster militaris A. Agassiz, op. cit. (?wn Miiller.) 



Pteraster cariihcBus Perrier, op. cit., 1881, p. 13; Etoiles de Mer, p. 216, 

 1884. 



Plate vii; figure 4. 



The radii of the type were 15°^ and 30°^°^ ; ratio, 1 :2. One be- 

 fore me has them 8™°^ and 12°^°^. The adambulacral comb of very 

 slender hyaline, webbed spines contains six or seven erect 

 spines, increasing in length outwardly, and another, the retro- 



