20 ECHINODEKMA. 



the ray. Marginal plates more or less alternate. Actinal inter- 

 mediate plates absent or scarce. 

 One genus : Pontaster. 



Subfamily 2. PLUTONASTERIN^E. 



Plutonasterinae, Sladen, Chall. Rep. Ast. (1889) p. xxviii. 



Archasteridae with papulae distributed over the whole abactinal 

 area. Marginal plates opposite one another. Actinal intermediate 

 plates well developed. 



One genus : Plutonaster. 



Family 2. PORCELLANASTERID.E. 



Porcellanasteridae, Sladen, J. Linn. Soc. xvii. (1883) p. 214 ; id. (sens, 

 emend.) Chall. Rep. Ast. (1889) p. xxix. 



Phanerozonia in which the calycinal plates are inconspicuous in 

 the adult, the abactinal plates spiniferous or paxilliform, and the 

 integument spiny ; the marginal plates are thin and lamelliform, 

 without spines. 



One subfamily. 



Subfamily OTENODISCIN^E. 



Ctenodiscinw, Sladen, Chall. Rep. Ast. (1889) p. xxx. 



Porcellanasteridae with a simplified cribriform organ on the 

 margins of each pair of marginal plates. Actinal interradial areae 

 traversed by fimbriated channels, continuous with those between 

 the marginal plates. 



One genus : Ctenodiscus. 



Family 3. ASTROPECTINIDiE. 



Astropectinidse, Gray, Ann. fy May. vi. (1840) p. 180; Norman, Ann. 



# Mag. xv. (1865) p. 115; Viguier, Arch. Zool. vii. (1878) p. 225; 



Sladen (sens, emend.), Chall. Rep. Ast. 1889, p. xxx. 

 " Dritte Familie," M. Tr. Syst, Ast. (1842) p. 13 (pars). 

 " Troisieme Section," Duj. $ Hup. Echin. (1862) p. 413 (pars). 



Phanerozonia in which the calycinal plates are inconspicuous in 

 the adult, the abactinal plates paxilliform, and the integument 

 spiny ; there is no anus, there are superambulacrals, short, more or 

 less compressed adambulacrals, and rarely pedicellariae. 



Two subfamilies. 



Subfamily 1. ASTROPECTINIM]. 



Astropectininee, Sladen, Chall. Rep. Ast. (1889) p. xxx. 

 Astropeotinidae in which the adambulacral touch the inferomar- 



