ai 



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

 the centre largest, nearly flat. The marginai ossicules f or | on 

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

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

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



Var, ? or young ? The ossicules of the orai surface near the edges 

 covered with granules. 



Inhab. Swan River. 



There is a specimen in the British Museum \vith six marginai 

 ossicules very likę the above, but diiFering from it in the dorsal 

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

 large marginai plate. 



TOSIA RUBRA. 



Red brown. Dorsal ossicules rather convex, rounded. Marginai 

 ossicules \% on each side, rather convex, equal, that at the tip of the 

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

 ■vvith a single series of marginai granules. 



Inhab. Australia. 



TosiA AUSTRALis, Gray, Ann. Nat. Hist. 



Yellowish or reddish. Dorsal ossicules rather convex, rounded. 

 Marginai ossicules f on each side, rather convex, equal ; the ossicules 

 of the orai surface flat-topped, with a single series of marginai gra- 

 nules. 



Inhab. W. Australia, Swan River. 



Petricia. 



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

 spineless. Back strengthened -vvith numerous, sunken, moderate- 

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

 but spineless ; the orai 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 likę Porania, but the back does not appear to 

 be angular, the margin is edged -vvith spines, and the ambulacral 

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

 of the back and orai 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 vvith convex lips. 



Petricia pūnctata. 



Orange, \vhen 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 Gortiaster Templetoni of Forbes, in the 

 British Museum from Arran, are exactly likę Asterias pulvillvs of 

 Miiller, received from Norway, in the šame coUection. 



