94 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



KEY TO THE KNOWN GENERA OF COSCINASTERI1NAE 



a 1 . Only the outer of the two inferomarginal spines carries a cluster of crossed pedicellariae. 

 b l . Adambulacral plates with two spines, at least on proximal half of ray; as a rule only two, or 

 equivalent of two, series of dorsolateral papular areas (by no means always regular) on 

 either side of carinal plates (alternate superomarginals usually spineless). 

 c'. Rays regularly only five in adults, but six in fissiparous young of some forms; odontophore 

 with single articulation pit on outer margin. (PI. 43, fig. 2.) 

 (P. Large spatulate, denticulate, straight pedicellariae; outer inferomarginal spines without 

 trace of a ventrolateral web; rays semicircular or heptagonal in section; dorsal 

 skeleton very irregular, the skeletal meshes not in two regular series on either side 

 of the carinal line of plates; dorsolateral spines developed in even tiny specimens; 

 they are numerous, in one or two irregular series on each side; adambulacral plates, 

 diplacanthid proximally, monacanthid distally. Type, Asterias sertulifera Xantus. 



Aslrometis Fisher. 



d 2 . Straight pedicellariae slender, lanceolate; outer inferomarginal spines connected in longi- 

 series by a continuous more or less fibrous web confined to base of spines, much 

 retracted in some dried specimens; rays pentagonal in section; dorsolateral skele- 

 ton regular, with two series of skeletal meshes on either side of the prominent cari- 

 nal ridge; dorsolateral spines usually late in developing and in only one series; 

 adambulacral plates with two spines throughout; the very young are fissiparous, 

 usually six-rayed, possibly reproducing regularly by fission. Type, Sclerasterias 



guernei Perrier Sclerasterias Perrier. 



c 2 . Rays seven to nine; so far as known not fissiparous; odontophore with 2 pits on outer 

 • margin (pi. 43, fig. 1); in general appearance similar to Sclerasterias but ray less 

 markedly pentagonal in section; a well-developed series of dorsolateral and actinal 

 spines; inferomarginal web absent or very rudimentary; only alternate superomar- 

 ginals spiniferous, the plates generally with a conspicuous beaded area (present also 

 in Sclerasterias and Astrometis) ; mouth angle rather narrow, with three to five 

 contiguous pairs of postoral adambulacral plates; straight pedicellariae medium to 



large, smooth or denticulate. Type, Margarasler scaber Hutton Astrostole Fisher. 



ft 2 . Adambulacral plates monacanthid throughout ray. 



c 1 . One series of spiniferous actinal plates; large straight pedicellariae with denticulate jaws. 



d 1 . Fissiparous, rays 7 to 12; skin covering skeleton not unusually thick and tough; crossed 



pedicellariae larger, with prominent lateral tooth to terminal lip; odontophore 



variable. Type, C. muricata Verrill Coscinasterias Verrill. 



e 1 . Alternate carinal plates oblong-elliptical, without lateral lobes; mouth angle very 

 constricted, with five or six contiguous pairs of adambulacral plates, behind the 

 mouth plates; odontophore, with one or two pits, or irregular, with several. (PI. 43, 



figs. 3, 3a) Subgenus Coscinasterias . 



e 1 . All carinal plates four-lobed; mouth angle broader, with two or three contiguous pairs 

 of adambulacral plates behind mouth plates, odontophore with one articulation 

 pit on outer border; first ambulacrals broader. (PI. 43, figs. 4, 4a.) Type, A slerias 



tenuispina Lamarck Subgenus Stolasterias Sladen. 



d 2 . Not fissiparous, rays five to seven; skeleton obscured by a thick tough skin; crossed 

 pedicellariae very small, round tipped, without enlarged lateral terminal tooth; 

 odontophore with two pits on outer margin. (PI. 43, fig. 7.) One series of spinif- 

 erous actinal plates; dorsolateral skeleton irregularly reticulated, the papular areas 

 equivalent to three or four longiseries, but only the lateralmost in a regular series; 

 abundant, large, broadly lanceolate, straight pedicellariae, with rather compressed 



denticulate jaws. Type, Asterias gelatinosa Meyen Meyenasler Verrill. 



c 2 . One series of small, spineless actinal plates hidden by skin. Not fissiparous; rays five; 

 dorsolateral skeleton normally fairly regular, the papular areas in two longiseries on 

 either side of the carinal series; dorsolateral and carinal spines either regular or very 

 irregular (africana) ; straight pedicellariae lanceolate, compressed. Type, Marthasler- 

 ias foliacea J Mien = Asterias glacialis Linnaeus Marthaslerias Jullien. 



