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. 
from whence this description of shell is 
called Nerita, may probably be derived from 
holloiv, the superior whorls occupying but a small 
share of the internal cavity. 
