V 



202 Zoological Society. 



those of the centre of the arms highest, those between the arm in 

 the centre largest, nearly flat. The marginal ossicules -£ or -| on 

 each side, convex, subtubercular, the one near the top of the arm 

 largest and oblong, longitudinal, convex. The ossicules of the oral 

 surface small, each surrounded with a single series of granules. 



Var. ? or young ? The ossicules of the oral surface near the edges 

 covered with granules. 



Inhab. Swan River. 



There is a specimen in the British Museum with six marginal 

 ossicules very like the above, but differing from it in the dorsal 

 ossicules being only convex and rounded ; it has the same convex and 

 large marginal plate. 



Tosia RUBRA. 



Red brown. Dorsal ossicules rather convex, rounded. Marginal 

 ossicules -f§- on each side, rather convex, equal, that at the tip of the 

 arms smaller, narrow. The ossicules of the oral surface flat-topped, 

 with a single series of marginal granules. 



Inhab. Australia. 



Tosia australis, Gray, Ann. Nat. Hist. 



Yellowish or reddish. Dorsal ossicules rather convex, rounded. 

 Marginal ossicules -f on each side, rather convex, equal ; the ossicules 

 of the oral surface flat-topped, with a single series of marginal gra- 

 nules. 



Inhab. W. Australia, Swan River. 



Petricia. 



Body convex, five-rayed. Skin above and below varnished and 

 spineless. Back strengthened with numerous, sunken, moderate- 

 sized ossicules ; the margin with two series of larger oblong ossicules, 

 but spineless ; the oral surface with rather regularly disposed smaller 

 ossicules. Ambulacral spines subulate, placed in pairs, with a second 

 series of similar but rather larger spines on the outer side of them. 



This genus is very like Porania, but the back does not appear to 

 be angular, the margin is edged with spines, and the ambulacral 

 spines are in pairs, and not single as in that genus. The ossicules 

 of the back and oral surface are punctured, and one of them situated 

 near the edge of the back, in the middle space between the arms, is 

 furnished with a linear pore edged with convex lips. 



^ i 



Petricia punctata. 



Orange, when dry. 



Inhab. the Reef of Attagor. J. B. Jukes, Esq. 



There is a single species of this genus in the British Museum col- 

 lection. 



I may here remark, that the specimen of Porania gibbosa, the Aste- 

 rias gibbosus of Leach, and Goniaster Templetoni of Forbes, in the 

 British Museum from Arran, are exactly like Asterias pulvillus of 

 Muller, received from Norwav, in the same collection. 



