98 



UNfVALVES. — NERITA. 



NERITA.— Nerite or Hoof-Shell. 



Aiiimal-^a Limax: Shell univalvey spiral, gibbons, Jiat- 

 tish at bottom; aperture semiorbicular or semilunar; 

 pillar-lip transversely truncate, fiattish. 



There are a few out of the seventy-six species which 

 compose this genus that have some claim to beauty, 

 though none can boast of great rarity or value. 



There is considerable variation in the form and markings 

 of the Neritae: some are spiral, with prominent whorls; 

 others have their whorls partly or wholly concealed; 

 some are greatly umbilicate or perforate ; others are per- 

 fectly entire and solid; and many have the umbilicus 

 partially covered by a repand lip, or fissurated nodu le. 

 The interior of the mouth and lips is, in many species, 

 tootldcss; whereas, in others, both lips are beset with 

 strong, prominent, and articulate teeth, often terminat- 

 ing in digointed, elevated striir, or protuberant granula- 

 tions. 



