4 BULLETIN 76, IMTED STATES NATIONAL MUSEUM 



a 1 . Adambulacrul spines devoid of attached pedicellariae, although large and small straight pedi- 

 cellariae maj occur on the surface of the plates or on fleshy peduncles attached to plate 

 u base of spines; clusters of the latter in dried specimens occasionally appear to spring 

 from the ath but in reality do not. 



6>. Abactinal skeleton an irregular net with meshes of various sizes, the plates being sometimes 

 closely but irregularly imbricated by their lobes; abactinal plates not in rather obvious 

 longitudinal serie but occasionally in more or less evident transverse series); carinal 

 series usually but not always distinguishable and frequently very irregular. 

 <•'. Adumbuhiei.il plates diplacanthid, at least at base of ray; rarely triplacanthid and tetra- 

 canthid. 

 (P. Grossed pedicellariae unusually large, the jaws narrow and rather definitely hooked 

 terminally; dorsolateral skeleton a very delicate and irregular meshwork which may 

 degenerate into more or less disconnected plates; marginal plates conspicuously 

 larger than dorsolateral; carinal and dorsolateral spines acicular, isolated; actinals 

 absent. 

 <'. Crossed pedicellariae very large, and of unusual form, with slender, serrate jaws ter- 

 minating in an unexpanded unguiculate tip; marginal spines prominent, acicular, 

 one to a plate, the inferomarginals with a very large cluster or cushion and the 

 superomarginals with a wreath of crossed pedicellariae; very numerous, large, 

 compressed-ovoid straight pedicellariae; gonads opening just above superomarginal 

 plates in interbrachial angle. Type, Asleracanthion linckii Midler and Troschel. 



Urasierias* Verrill. 

 e 1 . Crossed pedicellariae smaller with relatively stouter jaws, scattered thickly over the 

 abactinal and lateral surfaces, 6m/ not in icrealhs or clusters on the abactinal or 

 marginal spines; superomarginals monacanthid; inferomarginals diplacanthid, or 

 mixed monacanthid and diplacanthid distally; gonads opening just above supero- 

 marginal plates a short distance from base of ray. Type, Asterias panopla Stux- 



berg Icasterias* Fisher. 



cP. Crossed pedicellariae not unusually large, but small, with blunt, terminally spatulate, 

 denticulate jaws — the conventional type. 

 c 1 . Xo actinal plates; dorsolateral plates numerous, irregular, with small spinelets and 

 showing sometimes a tendency to form transverse series (usually, however, not 

 well marked); inferomarginal spines two to four in a transverse series, the con- 

 secutive combs closely placed. Inferomarginal spines bearing crossed pedicella- 

 riae; abactinal spinelets surrounded by a circlet of crossed pedicellariae. 

 /'. Papulae compound, each subdivided terminally into upward of eight small papillae; 

 inferomarginals diplacanthid, superomarginals monacanthid; adambulacrals 

 diplacanthid; not fissiparous; gonads opening just above superomarginals 

 abactinally in interbrachial angle; large unguiculate straight pedicellariae. 



Type, A phanasterias pyenopodia Fisher Aphanasterias Fisher. 



P. Papulae simple, undivided; inferomarginals with three or four spinelets in a trans- 



comb; superomarginals with several spinelets in a comb; adambulacrals 



triplacanthid, at least in part; strongly fissiparous, rays upward of eight; 



gonads opening between supero and infero marginal plates, low on side of ray, 



in the axillary channel; large bivalved dentate straight pedicellariae. Type, 



Asleracanthion albulus Stimpson Stephanasterias Verrill. 



P. Papulae simple, rays five, not fissiparous; gonads opening just above superomargi- 

 nals at a distance from interbrachial angle; adambulacrals diplacanthid; infero- 

 marginals and superomarginals with transverse comb of three or four spines 

 each; straight pedicellariae small, compressed, lanceolate. Type, Asterias 

 japonica Bell Aphela'sterias Fisher. 



