SHALLOW-WATER STARFISHES 53 



Genus Parasterias Verrill, nov. 

 Type, P. albertensis Verrill, British Columbia. 



Five rays, stout; dorsal plates openly reticulated, much as in 

 Asterias; interactinal spines and plates lacking ; adambulacrals dipla- 

 canthid. For more details see below, p. 187. 



Genus Ctenasterias Verrill, nov. 

 Type, C. spitzbergensis (Dan. and Koren). 



Dorsal skeleton composed of an irregular network of slender, but 

 numerous, mostly transverse ossicles, bearing large numbers of 

 minute, uniform spines, arranged in transverse rows or combs on 

 the sides of the rays. Marginal spines in two double rows near 

 together. Adambulacral plates diplacanthid, or partly triplacanthid. 

 Two forms of major pedicellariae ; the larger ones are lyrate or 

 cylindrical and obtuse. A single row of small interactinal spines. 

 Probably closely allied to Leptasterias. Reproduction not known. 



C. cribaria (Stimpson) is pretty certainly identical with the type, 

 which is from Spitsbergen. 



Genus Allasterias Verrill. 

 Type, A. rathbuni (Verrill). Bering Sea. 



Adambulacral spines alternately diplacanthid and triplacanthid, or 

 monacanthid and diplacanthid; the inner spine of the larger alter- 

 nate group is inserted on an angle of the plate within the edge of the 

 furrow. Dorsal skeleton openly reticulated; superomarginal plates 

 and spines form an angular margin. 



Genus Sporasterias Perrier. 



Type, S. antarctico (Liitk.)r=/i. rugispina Stimp. (teste Leipoldt). 

 Adambulacral spines regularly monacanthid. Dorsal skeleton 

 irregularly reticulated, sometimes nearly as in some species of Lept- 

 asterias, sometimes weakly developed. 1 Genital pores ventral ; the 

 eggs and young are carried over and around the mouth, as in Lept- 

 asterias. For details, see below, under Geographical Distribution, p. 

 355- 



Genus Smilasterias Sladen. 

 Type, S. scalprifera (Sladen). Off Patagonia, etc. 

 Adambulacral plates diplacanthid or triplacanthid, the spines and 

 those of the inferomarginal plates large, flat, and placed in transverse 

 rows. Dorsal skeleton irregularly reticulated with small spines. 



a ln S. rupicola Ver., from Kerguelen Island, the dorsal skeleton is well 

 developed, with short, stout ossicles and numerous small spines. 



