201 



marine shell : it is solid, semiglobular, concave beneath, 

 notumbilicated; aperture entire, semicircular; summit 

 very obtuse; left side flattened, (septiforme), sharp, 

 and often dentated, the inner one slightly concave, ge- 

 nerally with granulations; operculum fixed by a tooth 

 or appendage which fits into a receptacle within the 

 shell, opening as the animal passes out, and closing 

 upon it when retired within its shell. The shells are 

 never spined, but variously striated. They are gene- 

 rally so well known to collectors, that a more minute 

 description is here unnecessary. 



Nerita exuvia Nerita chamaeleon 



• textilis versicolor 



undata Ascensionis 



peloronta Malaccensis 



chlorostoma lineata 



atrata scabricosta 



polita plicata 



albicilla tessellata 



Nerita signata, 



