UNIVALVES. 



PLATE XXXIV. 



Genus. CASSIDEA. 



Character. Shell spiral, variously tuberculated, and sometimes spinous; the 

 mouth and cheek swelling out ; the spire short ; the columella fluted ; the cheek irre- 

 gularly notched within ; the rostrum short and deflexed ; no folds placed upon the 

 spire, which distinguishes it from the genus Cassis. 



Species. 



No. 1. Cassidea labiata. Shell ovate, pointed tapering, of a reddish brown co- 

 lour ; the columella yellow ; mouth brown. Found in the South Seas. From 

 the Collection of Mr. Rosse. 



No. 2. Cassidea bandata. Shell white and gray, having three bands in the front 

 of the body of a red colour ; the spire slightly tuberculous ; the cheek den- 

 ticulated, and spotted with red ; the mouth of a lively brown colour. The 

 form of this specimen is graceful and neat. It is a native of the East Indies. 

 From a shell in the Collection of Mr. George Spence. 



No. 3. Cassidea cornuta. Shell brown, and armed with horns, projecting ; 

 mouth pearl-coloured ; body striped with yellow bands, and brown crossing 

 lines ; the cheek armed with two horns. From a specimen in the Collection 

 of the Author. It has been figured by Regenfus, in his large Work of Con- 

 chology. 



Genus. NERITES. 



Character. Shell globular, the opening of the mouth semicircular, or shaped 

 like a half-moon; no spire; the beak small, and faintly marked; the columella 

 standing directly across the middle of the shell, making a sort of stage or platform, 

 and generally fluted. 



Species. 



No. 1. Nerites aurantia. Shell of a discoidal shape; the body olive colour, 



banded with pointed red spots running circularly round; mouth orange 



colour. Native place unknown. 

 No. 2. Nerites rubicunda. Shell of a pink colour, richly shaded with pointed 



lines of dark red ; mouth of an orange red ; the lip or border white. A 



native of the Eastern Seas. 



REMARKS. 



The genus Cassidea has a very considerable resemblance to the genus Cassis, before des- 

 cribed, but differs in not having any raised folds placed alternately upon the spire. 



The genus Nerites differs from the Helix by being rounder, and having a semilunar mouth ; 

 its spire, or at least the resemblance of it, sometimes appears marked upon the upper end of 

 the shell, as if it were sunk into the substance. The form and appearance in all the Nerites 

 are very much alike, and not very interesting in respect to beauty, we have therefore only 

 represented two species in the present description of the genus. 



