20 ECHINODERMA. 
the ray. Marginal plates more or less alternate. Actinal inter- 
mediate plates absent or scarce. 
One genus: Pontaster. 
Subfamily 2. PLUTONASTERIN Ai. 
Plutonasterinze, Sladen, Chall. Rep. Ast. (1889) p. xxviii. 
Archasteridee with papule distributed over the whole abactinal 
area. Marginal plates opposite one another. Actinal intermediate 
plates well developed. 
One genus: Plutonaster. 
Family 2. PORCELLANASTERID. 
Porcellanasteridee, Sladen, J. Linn. Soc. xvii. (1883) p. 214 ; td. (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 lamellitorm, 
without spines. 
One subfamily. 
Subfamily CTENODISCIN A. 
Ctenodiscine, Sladen, Chall. Rep, Ast. (1889) p. xxx. 
Porcellanasteridee with a simplified cribriform organ on the 
margins of each pair of marginal plates. Actinal interradial are 
traversed by fimbriated channels, continuous with those between 
the marginal plates. 
One genus: Ctenodiscus. 
Family 3. ASTROPECTINID A. 
Astropectinide, Gray, Ann. § Mag. 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. 18 (pars). 
“ Tyoisiéme Section,” Duj. § Hup. Echin. (1862) p. 4138 (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 pedicellariz. 
Two subfamilies. 
Subfamily 1. ASTROPECTININ A. 
Astropectininee, Sladen, Chall. Rep. Ast. (1889) p. xxx. 
Astropectinide in which the adambulacral touch the inferomar- 
