256 THE STELLEROIDEA 



spines. Marginal plates obscure. No pedicellariae. Genera Crossaster, 

 Mull. & Tr. ; Ctenaster, Per.; Lophaster, Verr.; Rhipidaster, Slad.; Solaster, 

 Forbes (Fig. XL). 



FAMILY 7. KORETHRASTERIDAE, Dan. & Kor. Characters " Crypto- 

 zonia allied to the Asterinidae, but distinguished by the complete absence 

 of interbrachial spaces, and by the possession of a continuous, calcareous 

 plating, and the formation of the paxillae" (Bell, 4, p. 23). Genera 

 Korethraster, Wyv. Thorns. ; Peribolaster, Slad. ; Remaster, Per. 



FAMILY 8. PTERASTERIDAE. " Cryptozonia in which the dorsal ossicles 

 carry a spine crowned by long diverging spines which support a more 

 or less well-developed membrane ; this forms a marsupial recess for the 



Fin. XI. 

 Abactinal surface of Solaster pappoaus. 



young. No actinal intermediate plates, interbrachial septa, or pedicel- 

 lariae" (Bell, 4, p. 23). In this family the most remarkable feature is the 

 development of a large marsupium in which the young are reared. This 

 is formed by a large veil above the abactinal surface, from which it is 

 raised by numerous long paxillae. The dorsal membrane is perforated by 

 many small pores (" spiracula," Sars), and has a large central opening, the 

 "oscular orifice." In some genera, e.g. Pttraster, there are also openings to 

 the actinal surface, known as " segmental apertures." There are often 

 long spine?, attached to the rays close by the adambulacral plates ; these 

 are known as the actino-lateral spines, and they are either enclosed in the 

 membrane of the actinal surface or in a marginal web. SUB-FAMILY 1. 

 CHEIROPTASTERINAE, with alternate ambulacral ossicles and short actino- 

 lateral spines. (The presence of the marsupium is not certain.) Form 



