NERITA. 103 



and cannot be confounded with the convex elabiate 

 side of the aperture, which is the generic distinc- 

 tion of the tribe of Helices. 



Nothing can exceed the beauty and delicacy of 

 the miniature painting with which many of the Ne- 

 ritse are adorned. When viewed with a magnifying- 

 glass, the most highly finished touches, upon the 

 smallest scale, are discernible on their enamelled 

 surface. The number of species and varieties 

 approximating to each other very closely, or only 

 differing in some one nice point, renders this genus 

 as difficult to be well arranged specifically, as it is 

 easy to be discriminated from other genera. 



This difficulty is much increased by the unifor- 

 mity of shape, especially in the last division ; for 

 it becomes necessary, where the outline is nearly 

 similar, to have recourse to the tones of colour for 

 specific marks. 



N»jg/V»)s, from whence this description of shell is 

 called Nerita, may probably be derived from wight, 

 hollow, the superior whorls occupying but a small 

 share of the internal cavity. 



