NERITA. 115 



ever, in all these individuals sufficiently evident, 

 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 

 Neritae are adorned. When viewed with a mag- 

 nifying-glass, the most highly finished touches, 

 upon the smallest scale, are discernible on their 

 enamelled surface. The number of species and va- 

 rieties 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 othergenera. 



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. 



NrigiTYig, from whence this description of shell is 

 called, may probably be derived from vrigos, hollow, 

 the superior whorls occupying but a small share 

 of the internal cavity. 



i2 



