Zoological Society, 195 



Aster ina gibbosa and A. Burtonii; with Pentaceros grandis, P. gibbus 

 and P. reticulatus ; with P. turritus and P. Franklinii, &c. &c. 



Culcita, Agassiz. 

 This genus chiefly differs from Randasia and Pentaceros in having 

 no upper series of marginal ossicules. It agrees with Randasia in the 

 back being nearly flat. p 



Culcita Schmideliana. fcr~ &- * 



A. Schmideliana, Retz. Dis. ; SchmideVs Naturf. xvi. t. 1. good. 

 A. discoidea, Lam. 



Body subcircular, flat above when dry (very convex subglobose 

 when alive). The back coriaceous, without any apparent reticula- 

 tions, covered with scattered, small, conical spines. The oral sur- 

 face rather convex (when dry), closely and minutely granular, and 

 with larger conical tubercles; those near the ambulacra and oral 

 angles much the largest and ovate. 



Inhab. ? 



There are distinct indications of the lower marginal ossicules in this 

 species, but they and the ossicules of the oral surface are not suffi- 

 ciently large and close to force the dry specimen to assume the pen- 

 tangular form of the following species. 



Culcita pentangularis. L *~ y ** 



Body pentangular ; back flat when dry, convex beneath, minutely 

 and closely granulated ; back with obscure reticulations, the reticu- 

 lations armed with small conical tubercles ; the interspaces closely 

 and minutely porous. The oral surface protected with distinct well- 

 defined ossicules, defining the lower edge of the margin, covered with 

 close and minute granules and larger round-topped tubercles, those 

 near the ambulacra and the oral angles being largest and highest. 



Inhab. Reef of Oomaga. 



This species is very distinct from the former, and forms the pas- 

 sage to the genus Randasia, but there is a series of concave, minutely 

 porous spaces in place of the upper marginal plates. 



Randasia, Gray. 



Body pentagonal, depressed, minutely granular ; back nearly flat, 

 minutely granular, reticulated ; reticulations rather tubercular, inter- 

 spaces sunken (when dry) and covered with very minute close per- 

 forations. Dorsal tubercles roundish, single, subcentral. Margins 

 furnished with an upper and lower series of oblong ossicules, the 

 upper one narrower internally, with a central series of tubercles, the 

 lower ones oblong, close together and convex. The oral surface 

 protected by close, regular, squarish, convex ossicules, covered with 

 short crowded granules. The ambulacral spines in rounded groups ; 

 the series of tubercles nearest the ambulacra larger, crowded, and 

 placed in groups of three or five, and those in the oral angles largest 

 and flat- topped. 



This genus differs from Pentaceros in the back being flat, elevated, 



14* 



