REPORT ON THE ASTEKOIDEA. 



175 



Synopsis of the Genera included in the Family Astropectinid^:. 



A. Adambulacral plates touching the infero-marginal plates along the ray. 



Marginal and adambulacral plates not correspondent in length and 

 number. Supero-marginal plates more or less well developed. No 

 forficiform pedicellariae ......... AsTROPEOTiNiNiE. 



a. With a webbed marginal fringe to the marginal plates, and to the 



actinal intermediate plates ......... Craspidasten 



b. With no webbed fringe to the marginal plates or the actinal inter- 



mediate plates. 

 a. Supero-marginal plates with a prominent ridge and specially 

 developed fasciolar channels. 

 a. Actinal interradial areas small, usually with few inter- 

 mediate plates. Paxillae with radiating crowns, 

 i. Marginal plates very short and band-like. Supero- 

 marginal plates much smaller than the infero- 

 marginal plates Leptoptychaste>\ 



ii. Marginal plates long and more or less quadrate. 



Superior and inferior series subequal .... Astropecten. 



|S. Actinal interradial areas large, with numerous inter- 

 mediate plates which imbricate and form trans- 

 verse columns. Paxillae small, with compact 

 erect crowns and long pedicles ...... Moirader, 



I. Supero-marginal plates plane, with no ridge and no specially 

 developed fasciolar channels. 

 a. Spinulation simple, not sacculate. Adambulacral arma- 

 ture forming a straight series on the furrow mar- 

 gin, spinelets numerous and uniform ..... Psilaster. 



j6. Spinulation sacculate. Ambulacral armature forming 



an angulated series on the furrow margin, the 



spinelets few in number, and the median one of 



a different shape from the rest. 



i. Well-developed epiproctal cone. No pedicellariae . . , Phoxaster. 



ii. No epiproctal cone. Sacculated spinelets of the 



actinal area forming modified pedicellariae . . . Bathybiaster. 



B. Infero-marginal plates separated from the adambulacral plates by a small 



intermediate plate throughout the ray. Marginal and adambulacral 



plates correspondent in length and number ..... Luidiina 



a. Supero-marginal plates aborted. Adambulacral plates not separated by 



a fimbriated channel. Forficiform pedicellariae present .... Luidia. 



b. Supero-marginal plates present. Adambulacral plates separated by a 



fimbriated channel. No forficiform pedicellariae present .... Platasterias. 



Subfamily Asteopectinin^;, Sladen, 1887. 

 Genus Craspidaster, n. gen. 



Archaster (pars), Miiller and Troschel, Monatsber. d. k. Akad. d. Wiss. Berlin, 1840, p. 104; System 

 der Asteriden, 1842, p. 65. 



Rays five, tapering, subrigid. General form subdepressed and fiat. 



Supero-marginal and infero-marginal plates largely developed, remarkably thick and 



