CONCHOLOGY. 123 



3. Nerita. The Hoof Shell. Seventeen species. 

 A marine shell, never spined, but variously striated. 

 Some species of this genus are very beautiful ; they are fre- 

 quently worn as ornaments by the Indians. 



Shell solid, thick, more or less globular, flat beneath, spire 

 but little, if at all, projecting, not umbilicated ; aperture 

 large, semilunar, very entire ; the external margin very much 

 hollowed ; the internal or columellar straight, sharp, and 

 shaped like a partition, often dentated ; operculum horny or 

 calcareous, sub-spiral ; the summit entirely marginal at its 

 extremity, implanted by teeth more or less marked, and 

 sunk in the columellar margin, on which it seems articu- 

 lated. 



Nerita exuvia. Nerita chamasleon. 



N. textilis. N. versicolor. 



N. undata. N. Ascensionis. 



N. peloronta. N. Malaccensis. 



N. chlorostoma. N. lineata. 



N. atrata. N. scabricosta. 



N. polita. N. plicata. 



N. albicilla. N. tessellata. 



N. signata. 



N. peloronta. The bleeding-tooth Nerita. PI. 21, fig. 5. 



Thick, transversely sulcated ; inner lip with two crenula- 

 tions, with a bloody mark at their base ; under lip with two 

 notches near its internal upper edge ; colour yellowish, tinged 

 with red, with variously coloured bands. 



N. exuvia. The exuvia Nerita. 



Species with the inner hp toothed and tuberculated. 



N. polita. The smooth Nerita. 



Species with both lips toothed ; beautifully distinguished 

 by having three or four bright crimson bands, on a dark mot- 

 tled ground, running in a parallel direction with the convo- 

 lutions of the shell. A favourite Indian ornament. 



