106 CONCHOLOGY. 



FAMILY XL 



Neritacea. Four genera. 



1. Genus JVeritina. PL X. 

 Animal. Globular ; foot circular, thick, without a furrow ante- 

 riorly, or a lobe for the operculum posteriorly, with a bipartite 

 columellar muscle ; conical tentaculae ; eyes subpedunculate at 

 their external side ; mouth without labial tooth, but with a denti- 

 culated tongue prolonged into the visceral cavity ; a single large 

 pectiniform branchia. 



Shell. This genus was formerly classed with the Nerita, which 

 in form it much resembles, but from the circumstance of the latter 

 inhabiting the sea, and Neritinae fresh water ; it now forms a 

 separate genus, thin, smooth, or finely striated, in all the species 

 known, the right side of the aperture does not possess any crenula- 

 tions or teeth; the operculum is provided with a lateral tooth on 

 one side. Some species are armed with spines; aperture semi- 

 circular ; left margin smooth and sharp ; spire imperfect, generally 

 dissolved by the animal. Inhabits the fresh water rivers of 

 Europe. Twenty-eight species. 



Neritacea puversa. Neritacea semiconica. 



N. pulligera. N. strigilata. 



N. dubia. N. meleagris. 



N. zebra. N. virginea. 



N. zigzag.- N. fluviatilis. 



N. gagates. N. viridis. 



N. lugubris. N. Baetica. 



N. lineolata. N. Oweniana. 



N. fasciata. N. careosa. 



N. Domingensis. N. caffra. 



N. auriculata. N. Smithii. 



N. crepidularia. N. spinosa. 



N. brevispina. N. Oweni. 



N. corona, N, pulchella. 



