228 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



with flattish, polygonal, compact granules (spinelets on inferomar- 

 ginals of gracilis) ; compact, polygonal, actinal intermediate, and 

 subambulacral granules, rather than spinelets; and in lacking the 

 postadambulacral fascicles. 



The " postadambulacral fascioles " are identical with those of 

 Pseiidarc'haster and are now known to be incipient pedicellariae. 

 In Pseudarchaster they are in some species constantly present, while 

 in others they are not; not all species have them. In Aphroditaster 

 the fasciolar pedicellariae are not of generic importance, as shown 

 by their presence in A. gracilis and their absence in the present 

 species. 



Aphroditaster agrees with Pseudarchaster in general appearance 

 and in having an odd tooth at the inner end of the combined mouth 

 plates. It differs in having a straight or only slightly curved furrow 

 margin to the adambulacral plates, an even comb of furrow spines, 

 and no specialized or enlarged subambulacral spine or spines. The 

 two genera are very close, and I doubt if the young of some species 

 of Pseudarchaster could be distinguished generically from young 

 A f hroditaster. 



Genus PARAGONASTER Sladen. 



Paragonaster Sladen, 1889, p. 310. Type, P. ctenipes Sladen. 



KEY TO THE SPECIES AND SUBSrECIES OP PARAGONASTER HEREIN DESCRIBED. 



a\ Proximal plates of the single series which separates the superomarginals 

 wider than long, and conspicuously wider than the adjacent radial plates 

 of disk ; peripheral granules of the plates of papular area smaller than 

 the central granules ; the two sorts subequal elsewhere ; central granules 

 slightly spaced, not compact ; numerous inferomarginal and actinal intex*- 

 mediate spines ; f asciolate pedicellariae between nearly all the adambu- 

 lacral plates hypacantlius, p. 228. 



a". Proximal plates of the radial series of ray narrower than long and narrower 

 than the adjacent x'adial plates of disk; peripheral granules of all the 

 abactinal plates smaller than the central, which are very compactly 

 placed ; very few inferomarginal and no actinal intermedhite spines ; 

 incipient fasciolate pedicellariae between the first few adambulacral 

 plates only, rudimentary distally stenosticJitis, p. 232. 



PARAGONASTER CTENIPES HYPACANTHUS, Fisher. 



I'late 70, fig. 3 ; plate 71, fig. 2 ; plate 72, fig. 1 ; plate 91, figs. 9, 9a. 



Paragonaster ctenipes hypacantlius Fishek, 1913rt, p. 627. 



Diagnosis. — Closely resembling P. ctenipes Sladen, but differing 

 in having more numerous granules on the abactinal plates, more 

 numerous and conspicuous inferomarginal spinules and smaller and 

 more distantly spaced inferomarginal granules, a prominent central 

 spine on many of the actinal intermediate plates, and proximally 2 

 enlarged subambulacral spines. R=88 mm., r=19 mm., R=4.6 r; 



