38 NEEITELLA. 



Family NERITIDJE. 

 Genus NERITELLA, Humphrey. 



Shell globular, or globose-conical, thin, with 

 a horny epidermis, and a large semilunar aper- 

 ture, the inner lip of which is straight and 

 flattened with a smooth or denticulated mar- 

 gin, outer lip-margin rounded, simple, acute. 



Operculum sub-spiral, testaceous, smooth on 

 the exterior surface, with two apophyses or 

 ridges, of which the upper one is short, and 

 the lateral one in the form of an arched rib. 



Animal. Head with a short, broad muzzle, 

 slender tapering tentacles, with pedunculated 

 eyes at their outer bases ; foot oblong, triangu- 

 lar, the sides simple. 



Distribution^ — Tropical and subtropical. 



Most of the species belonging to this family 

 and genus are marine, many of them, however, 

 inhabiting brackish water. Of the six species 

 described and figured in Mr. Binney's recent 

 publication on the "Land and Fresh- Water 

 Shells of North America,"* three, viz. : cassicu- 



* Smithsoniaa Miscellaneous Collections. 8vo. Wash- 

 ington, D. C, 1865. 



