35*2 APPENDIX. 



Petricia, Gray. 



Body convex, five -rayed. 



Skin above and below varnished, spineless. 



Back strengthened with numerous sunken moderate- 

 sized ossicules ; the margin with two series of larger oblong 

 ossicules, 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 not 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. 



Petricia punctata, n. s. 



Orange when dry. 



Inhab. — The Reef of Attagor. J. B. Jukes, Esq. 



There is a single specimen of this genus in the British 

 Museum collection. 



I may here remark that the specimen of Poraria gibbosa, 

 the Asterias gibbosus of Leach^ and Goniaster Templetoni of 

 Forbes, in the British Museum, from Arran, are exactly like 

 Asterias pulvillus of M tiller, received from Norway, in the 

 same collection. 



Patiria, Gray. 



This genus may be divided into three sections. 



1. Body pentagonal, the dorsal ossicules lunate narrow, 

 the edge of the arms acute. The space of the upper side 

 between the angles of the arms are covered with small 

 roundish groups of spines. 



