ASTEROIDEA OP NORTH PACrFIC AND ADJACENT WATERS FISHER. 253 



(P. Interbrachial Bepta rudimentary, sometimes partly calcified;" adanibulacral Bpinca delicate, 

 webbed, not associated with inferomarginal spines; ahactinal and lateral plates very deli- 

 cate, imbedded in the integument, bearing groups of delicate short or long spinelets 



united by a web or imbedded in a sacculua Hijianleridx.^ 



c'. A complete eupradorsal membrane present; segmental pores and papillie; interbrachial septa 

 not calcified ;c actinolateral spines present PlerasU-ridx, p. 343. 



Family ASTERINID^E Gray 1.S40, ememleil. 



Asterinidse Gray, Ann. and Mag. Nat. Hist., vol. G, 18-10, p. 228 (includes Palmipes, Porania, 

 Asteriiia, Paliria, Socomia). —Verrier, Revision des SlelMrides, 1875, p. 289; Mission sricntif. 

 Cap Horn, 1891, p. 107 (includes Porania, Gancria, and allies'); Exp. sci. du Traraillntr et du 

 Talisman, 1891, p. Ml.— Sl.\den, Challenger Astemidea, 1889 (includes Ganeriina').—FisnER, 

 1906 (excludes Anseropodinai+Tremaiilerina;). 



Spimilosa with dorsal skclctou formed of imbricating j)latc3 bearing small 

 spinelets or granules singly or in groups or tufts; with regular imbricated actinal 

 intermediate ])lates bearing a few spinelets or granules, sometimes iu combs; mar- 

 ginals minute, usually defining ambitus. 



KEY TO THE SUBFAMILIES A.ND KNOWN GE.VERA OF ASTERINID.E. 



a'. Papulae distributed widely over disk and radial regions; no aperture in each intcrradius perforating 

 the di.'ik as in keyhole sand-dollars (Mellita); abactinal plates externally crescentifomi, thick, 

 bearing granules or short spinelets; plates outside papular areas not thin and scale-like, with 



internal process Asterininx Sladen. 



i'. Abactinal plates not imbricated; covered with spines ParasUrina ^ Fisher 



h-. Abactinal plates imbricated throughout the abactinal area, or only in definite regions, 

 c'. Rays cylindrical, more or less elongate; disk small; with a definitely and sharply defined band 



of crescentifomi plates along the median areas of the rays Nepanthia Gray. 



c'. Rays and body flattened; disk large with shaqily angular edges. 

 d'. Abactinal plates imbricated by three or four fairly regular internal processes or lobea and 

 bearing on exposed more or less crescentiform surface, or on free edge, granules or short 



spinelets; all abactinal plates subsimilar Aslerina Nardo, p. 2-54. 



d'. Abactinal plates imbricating only near the margin, the others spaced apart; covered with 



naked skin Disasterina Perrier. 



o'. Papula; confined to comparatively narrow radial band; plates of. papular area strongly stellate, 

 imbricating, the others thin, scale-like, strongly imbricating, the internal edge pointed and pro- 

 longed downward into a process which meet.s a similar process from a ventral plate and forms a 

 doreo-ventral supporting pillar for the very thin disk; general form of dorsolateral plates broadly 

 lanceolate Anseropodinx' Fisher. 



o Sladen (1889, p. xlii) and Bell (1892, p. 4) imply that septa are absent. They are present but 

 do not extend far toward center of disk, and contain calcareous plates. 



6 This family iuclu<ies the Pythonasterina; with one genus, Pythonaster Sladen, and M yxasterinie 

 with two genera, Myxaslcr Perrier, and the even more remarkable Asthcnaclis Fisher. 



cThe Pterasteridic are said to lack interbrachial septa. These arc present in several species of 

 Plcrasler (as, for example, jordani and Usselatiis) and in llymenaster kahlfri, but arts not calcified. 

 The interbrachial septa of //. qiiadrispinosM have small thin embrj-onic plates, which are not visible 

 unless the membrane is examined under a microscope. Such a condition will not be readily confused 

 with an ordinary calcareous or partly calcified septum. See Sladen 1SS9, p. xlii. 



dThis genus is equal to Patina of authors, not of Gray. Gray's Patiria is a synon>-m of AtUrina. 

 Fisher, Smiths. Misc. Coll. (Quarterly^ vol. 52, no, 1799, I9as, p. 90; Zool. An?.., 18 Aug., 19a>*,p.358. 



« Bull. U. S. Fi.sh Comm. for 1903, pt. 3, 190(i, p. 10S7, f(X)tnote. 1 now think it is better to keep 

 the three subfamilies in one family, and segregate Vycethra, Oaneria, and liadiatter as Perrier baa done 

 (1894). 



