CONCHOLOGY. 121 



A. carinata. The carinated Ampullaria. 

 Species sinistral, with a very large umbilicus, spirally car- 

 inated. 



FAMILY XI. 



Neritacea. Five genera. 

 1. Neritina. Twenty-one species. 



Formerly classed with the Nerita, but separated from it 

 because the Nerita is a marine shell, and those of this genus 

 are fluviatile. 



They are generally thin, smooth, or very finely striated ; 

 the right side of the aperture is not crenulated or dentated, 

 and the animal dissolves the interior of the spire. 



Shell thin, ovate, not umbilicated ; aperture semilunar ; in- 

 ner lip reflected on the columella, and sometimes crenated ; 

 outer lip without teeth internally ; operculum with a lateral 

 tooth. 



Neritina perversa. Neritina auriculata. 



N. puUigera. N. Domingensis. 



N. dubia. N. fasciata. 



N. zebra. N. lineolata. 



N. zigzag. N. semi-conica. 



N. gagates. N. strigilata. 



N. lugubris. N. meleagris, 



N. corona. N. Virginea. 



' N. brevi-spina. N. fluviatilis. 



N. crepidularia. N. viridis. 

 N. Baetica. 



'f.fiumatilis. The fresh-water Neritina. 



Shell very small, oval ; back convex, smooth, white, with 

 black or brown spots ; spire inclined, lateral lip slightly den- 

 ticulated; right edge sharp, operculum very oblique. 



N. zebra. The zebra or striped Neritina. PL 21, fig. 2. 

 Same as N. fluviatihs, but striped instead of spotted. 



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