300 VERRILL 



each plate. The dorsal and marginal plates are large, convex, bor- 

 dered or covered with large granules, and often have one or more 

 central tubercles or stout spines ; no fascioles. 



Bivalve pedicellariae having short, broad valves, and often of large 

 size, are usually present, both on the dorsal and actinal plates, and 

 often on the marginals ; smaller spatulate forms also occur. 



The abactinal plates are thick, rather closely joined, and polygonal 

 or roundish, usually unequal, with small intermediate secondary 

 plates. 



The actinal plates are numerous, tesselated, and covered with 

 large granules, at least around the margin, and usually have either 

 a large valvular pedicellaria or else a short, thick spine or tubercle 

 in the middle. Superambulacral plates are lacking. 



In this subfamily I include Cladaster Verrill, not included by 

 Fisher. It lacks the large dorsal and marginal spines or conical 

 tubercles of Hippasteria, and the dorsal ossicles are all of one kind. 

 Fisher describes (1911^, p. 22, pi. xli, figs, i, 2) C. validus, Fisher, 

 from off the Aleutian Islands, in 283 fathoms. 



Genus Hippasteria Gray. 



Plate XLVH ; plate XLvni, figures 1-5 (details of type species); plate xux, 



figure 6. 

 Goniaster (pars) Agassiz,' Prodromus, Mem. Soc. Sci. Neuchatel, i, p. 191, 



1835 (non Gray, 1840). Forbes, Brit. Starfishes, p. 122, 1842. Norman, 



Ann. and Mag. Nat. Hist., xv, p. 123, 1865. 

 Hippasteria Gray, Ann. and Mag. Nat. Hist., vi, p. 279, 1840; Synopsis, p. 9, 



1866. 

 Hippasteria Perkier, Arch. Zool. Exper., v, p. 86, 1876. Viguier, Arch. Zool. 



Exper., vu, p. 176, 1878 (structure). Sladen, Voy. Challenger, Zool., xxx, 



p. 341. 1889. Verrill, op. cit., 1899, p. 174. Fisher, op. cit., 191 1&, p. 223. 

 Astrogonium (pars) Muller and Troschel, System Asteriden, p. 52, 1842. 

 Hippasterias Bell, Catal. Brit. Echinod., p. 76, 1892 (spelling incorrect). 



Disk broad, rather flat, subpentagonal, with short rays, and con- 

 cave interradial margins. Marginal plates of moderate size, thick, 

 convex, regularly paired, surrounded by a marginal row of granules 

 and usually bearing one or more short, stout spines or tubercles, and 

 sometimes, also, a wide, bivalvular pedicellaria. Dorsal or abactinal 

 plates mostly large, more or less convex, thick, tesselate, subpolyg- 

 onal or roundish, with marginal granules, and bearing one or more 

 thick central spines or tubercles, or else a wide bivalved pedicellaria ; 

 many small secondary, granulated plates are interspersed between 



' See note, p. 286, for original contents of Goniaster Agassiz. 



