SHALLOW- WATER STARFISHES 47 



ance it resembles Coronaster, but the latter has only two rows of 

 ambulacra! feet. I would suggest Heterasterias, as a genus; type, 

 H. volsellata. 



Genus Marthasterias Jullien. 



Marthasterias Jullien, Bull. Zool. Soc. France, p. 141, 1878. 

 Stolasterias {pars) Sladen, Voy. Challenger, xxx, p. 563, 1889. Perrier, Voy. 

 Trav. et Talism., pp. 108, 109; Resultats Camp. Scient., i, p. 34, 1896. 



Rays five, angular, normally with three dorsal radial rows, besides 

 the superomarginal rows, of stout plates bearing large, mostly conical 

 spines; usually two on the superomarginals. Inferomarginal plates 

 usually with two rows of spines. Adambulacral plates generally 

 monacanthid, each plate with a single spine. Peractinal ossicles 

 small and without spines, scarcely visible externally.' When young 

 it has only one row of dorsal spines, the median, developed; when 

 very large there may sometimes be more than three rows. 



Besides the type, M. glacialis Miiller, this group includes 

 M. africana, of South Africa, and M. rarispina (Perrier). 



The allied diplacanthid species were referred to another generic 

 group (Distolasterias) by Perrier. 



Genus Distolasterias Perrier. 

 Distolasterias Perrier, Resultats des Camp. Scient., i, p. 34, 1896. 



This name was proposed by Perrier for a group of which Stol- 

 asterias stichantha Sladen, of Japan, was the type. It is distin- 

 guished from his Stolasterias = Marthasterias by the diplacanthid 

 arrangement of the adambulacral spines ; and by having five or more 

 regular close longitudinal rows of dorsal plates. The actinal plates 

 are rudimentary and without spines. 



But the Stolasterias neglecta of Perrier ( 1896, p. 37, pi. i, figs. 2, 

 2a, 4-4C) is diplacanthid and therefore does not go in that genus, as 

 he defines it, for in the same work (op. cit., p. 35) he makes the 

 genus monacanthid. In this respect neglecta is like his Distolasterias 

 (op. cit., p. 34), but the type of the latter has a much more complex 

 dorsal skeleton, with five or more rows of dorsal plates and spines. 

 S. neglecta apparently belongs with a group of which A. forreri Lor. 

 may be taken as the type. 



' For description and figures of skeleton, see Viguier, op. cit., pp. loo-ios, 

 pi. V, figs, i-io, 1878. 



