ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER. 171 



<P. No secondary abaetinal platea; no int^rniarginal plates, 

 e'. Actinal intermediate plates without spines, or with only low tiilierrlea; platea at least 

 centrally bare; the smooth marginals with one or more rigid spines or tuliercles. 

 /'. Disk flat but fairly thick; no abaetinal pedicellaria;; actinal spines without swollen 



multiiid or bifid points Calliaslcr Gray. 



p. Disk very thin, rigid, flat; actinal spines with swollen multitid or bifid points; spatulate 



pedicellaria; on both surfaces of Ixidy Millfliphaster Alcock. 



e^. Actinal intermediate and inferomarginal plates with appressed movable sharp spines; 

 all plates granulated; no tubercular marginal spinea; radial abaetinal spines present in 



one species Callidtrma Gray. 



6'. Only a pentagon of five short tubercles on disk, or more often none; never any abaetinal spines 

 on rays; no superomarginal spines, 

 c'. Abaetinal plates of rays not abruptly and conspicuously larger than those of disk, 

 (f. No inferomarginal and actinal intermediate spines. 

 «'. Marginal plates of both series not regularly decreasing in size from interradius to apex of 

 ray, but increasing eitlier slightly or markedly. Sometimes the last marginal is en- 

 larged; sometimes the second, third, or fourth plate from the end is largest, and the 

 marginals are graduated in breadth on Iwth sides of this, abruptly toward the apex and 

 verj- gradually toward a point between the enlarged plate and base of ray; the en- 

 larged plate is always either appreciably longer or wider (or both) than the preceding 

 or succeeding plates. 

 p. Pedicellaria; never lji\alved; no tubercles on disk; papulae not in areas, single; outlines 

 of plates distinct; abaetinal interradial plates not conspicuously enlarged. 

 51'. Last marginals of both series enlarged; abaetinal, marginal, and actinal intermedi- 

 ate plates smooth, sUghtly convex (never tabulate) bordered l>y a single series of 



granules PentagonasUr Gray. 



ff^. Not the ultimate but the penultimate or antepenultimate marginal of both series en- 

 larged; abaetinal and actinal plates flat and closely granulated; marginals with 



scattered granules in pits Sphseriodiscus Fisher. 



y. Abaetinal interradial plates (four in each interradius) enlarged; five primarj' radial tu- 

 bercles on disk, forming a pentagon; bivalved pedicellariae of small size on abaetinal, 

 marginal, and actinal intermediate plates, largest on latter area; abaetinal plates with 

 minute pincers also; all plates closely granulated; abactinals stellate (no secondary 

 intermediate plates); papular areas with three to five papular pores (except near end 

 of ray where only one or two), granulated, and bearing one or two minute pincers; 

 actinal interradial areas large; adambulacralplateswithfive to eight slender graduated 

 marginal spinelets and a row of two or three elavate or oblong rounded granulifonn 

 spinelets just behind tlie furrow series; ra)-s slightly swollen near tip or with parallel 

 sides; tliird or fourth marginal from apex the largest; outlines of abaetinal and actinal 



intermediate plates not distinct Goniodiscasta- Clark. 



e*. The marginal plates evenly graduated in size, or if the ultimate or penultimate is en- 

 larged, only in upper series. 

 /'. Numerous tlistal marginals not united to form long slender rays. 



g'. Secondarj' plates of small size interpolated between the primarj- abaetinal plates, 

 /i'. Abaetinal plates fiat, either smooth or granulated, but not tabulate or paxilliform. 

 i'. Abaetinal plates small, closely granulated; furrow spinelets not spaced from 

 actinal ones, nor sharply differentiated; bivalved pedicellarice. 



Pcltastcr \'errill. 



i". Abaetinal plates naked centrally, but surrounded by a single series of granules 



on radial areas (over interradial areas granules may be only scattered around 



edge of plate, or absent); adambulacral plates with sharply differentiated 



furrow series; no bivalved pedicellariae, but a few small chisel-bladed ones 



on adambulacral plates Plinlhasler (inel. Pyrcnastcr) Verrill. 



h'. Abaetinal plates tabulate on radial areas, suggesting low paxilla-. Seeondarj- 



plates present only in adult specimens Ceramaslcro Verrill, p. 204. 



g'. No secondary plates on radial areas; sometimes a few on center of disk. 



" C. hptoceramns Fisher. 



