New Genera of Starfishes. 171 



XXIV. — New Genera of Starfishes. 

 By Walter K. Fisher, Stanford University, California. 



The following genera will be described in detail and figured 

 in an extensive report on the Asteroidea of the North Pacific, 

 now in preparation. 



T HRISSACANTHIAS, gen. nov. 



Astropectinidae near Pers'phonaster, Alcock, but differing 

 in the arrangement of gonads, which are not confined to the 

 interradii, but extend for a short distance on either side along 

 ray as a number of distinct tufts depending from the genital 

 stolon ; adambulacral plates with 1 or 2 enlarged actinal 

 spines ; disk of medium size, depressed, rays long ; abactinal 

 surface with true paxillaa arranged in regular oblique trans- 

 verse rows ; no enlarged radial series ; papula? all over 

 abactinal surface, except at tip of ray; actinal intermediate 

 plates extending far along ray ; interradial areas rather small ; 

 spiniform fascicular pedicellarue on marginals : anus present; 

 madreporic body large, not hidden. 



Type, Persephonavter penicillatus, Fisher, Bull. Bureau of 

 Fisheries, 1904, xxiv. 1905, p. 297. Off Los Coronados 

 Islands, Lower California, 530 fathoms. 



Gephyreaster, gen. nov. 



Mimasteiina? related to Mimaster, Sladen, but differing in 

 having stout tabulate paxillas with strongly stellate bases by 

 which the plates overlap; in the character of actinal inter- 

 mediate plates, which, instead of bearing small tufts of spines 

 forming spaced paxillae, are densely covered with spinelets ; 

 in the armature of the mouth-plates, which have a peculiar 

 angular marginal series situated between peristome and 

 superficies of plate on inner end; superambulacral plates 

 present. Marginal plates, adambulacral plates, and armature 

 similar to those of Mimaster, the first without enlarged 

 spinules. 



Type, Mimaster swfti, Fisher, Bull. Bureau of Fisheries, 

 1904, xxiv. 1905, p. 301. Stephens Passage, Alaska, 188— 

 ]31 fat bonis. 



This genus is intermediate in many respects between 

 Mimaster and P seudar chaster , but is nearer to the former. 



SPH^RIODTSCUS, gen. nov. 



Goniasterinae differing from Pentagonaster, Gray (type, 

 P. i>ulchellus) , in having the abactinal an.l actinal plates 



