30G BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



KEY TO THE KNOWN GENERA OF SOLASTERrD.E. 



a'. Marginal paxilla; in cither one or two series, but if in two then only the inferomarginals well devel- 

 oped, the superomarginals being much smaller, and similar to but larger than abactinal paxillse. 

 Rays more than five. 

 6'. Superomarginal plates, it distinguishable, in a series distinct from inferomarginals; not one or 

 two superomarginals alternating with one inferomarginal in a single linear series, 

 c'. Abactinal plates not independent, but joined by their lobes, or by means of secondary inter- 

 mediate o^^icles. 

 rf". Actinal intermediate plates extending only part way along ray, or confined to disk and not 



bearing a comb of spines but a paxilliform tuft Solaster Forbes, p. 306 



rf^. A complete series of actinal intermediate plates, each bearing a curved comb of spines, extend 



ing to end of ray Rhipidasler Sladen 



(r. Abactinal plates small, unequal, roundish, very numerous and independent. Actinal inter- 

 mediate plates extending nearly two-thirds length of ray Lxtmastero Fisher 



b-. Marginal plates of two kinds in a single linear series — conspicuous transversely oriented, promi- 

 nently spinous, paxilliform plates alternating with one or two low, longitudinally placed plates 

 with short spinelets; small actinal intermediate plates extending to end of ray; abactinal 

 skeleton wide meshed ; paxillse small; papula; numerous and large. . Heterozonias Fisher, p. 330. 

 a*. Marginal paxillse in two prominent, nearly equally developed series, rays 5.Lophasterb\emll,f.3Zi. 



Genus SOLASTER Forbes. 



SolasUr Forbes, Mem. Wemerian Soc, vol. 8, 1839, p. 120. Type, Asterias endeca Linnaeus. 

 Crossaster Muller and Troschel, Monati^ber. preuss. Akad. Wiss. Berlin, April, 1840, p. 103; 



Archiv Naturgesch., 6 Jahrg., vol. 1, 1840, p. 183. Type, Asterias papposa Linnseus. 

 SolasteT (subgenus Endeca) Gray, Ann. and Mag. Nat. Hist., vol. 6, 1840, p. 183. Type, Solaster 



endeca. 

 Solaster (subgenus Polyaster) Gray, Ann. and Mag. Nat. Hist., vol. 6, 1840, p. 183. Type, Solaster 



papposus. 



Diagnosis. — Solasteridse with one series of well developed marginal paxillae, 

 the superomarginals being always markedly smaller than th« inferomarginals; 

 abactinal skeleton of cruciform or stellate plates, either closely placed or forming, 

 by means of slender intermediate ossicles, an open meshwork. Abactinal pseu- 

 dopaxillsB spaced or crowded, small to large, fascicular, tabulate, or penicillate. 

 Actinal intermediate plates extending more or less along ray. Rays seven to 

 fourteen. 



<^Lsetmaster Fisher, Smiths. Miscell. Coll. (Quarterly Issue), vol. 52, 1908, p. 88. This is a substi- 

 tute name for Ctenaster Perrier; type, L. spectabilis (Perrier). L. Agassiz, in the M^m. eoc. sci. nat. Neu- 

 chatel, vol. 1, 1835, p. 192, used Ctenaster as a substitute name for Asterina Nardo, 1834. Its status 

 corresponds to that of Cribrella. This prior use of Ctenaster ("Once a synonym, always a synonym") 

 necessitated the renaming of Perrier's genus. 



I examined the type in the Museum of Comparative Zoology (No. 910). Perrier, in my opinion, 

 has overlooked the chief character by which this form may be separated from Solaster, namely, the 

 structure of the abactinal skeleton. The presence of actinal intermediate plates "rather far along the 

 ray " upon which he places primary importance may be duplicated in Solaster (in its narrowest sense). 

 But the abactinal plates are very many, small, unequal, delicate, and roundish, with a low column 

 bearing three to six delicate sharp diverging spinelets. They appear to be quite independent, and 

 not forming a meshwork as in other genera of the Solasteridse. Papulae extending half way to end of ray. 



b Including Sarkaster Ludwig. 



