CONCHOLOGY. 1 13 



P. sinistrosa.* P. hyalina.* 



P. Nuttaliana.* P. unicolor.* 



P. virens.* P. nuclea.* 



P. pallida.* P. decisa.* -^ 



P. subcarinata.* P. fuscus.* 



P. genicula,* P. dissimilis.* 



P. magnifica.* P. ponderosa.* 



P. liniosa.* P. Integra.* 



P. subglobosa.* P. porata.* 



P. lapidaria.* P. lustrica.* 



P. Virginica.* P. grana.* 

 P. Nickliniana.* 



3. Genus Ampullaria. PL X. 



Animal. Inflated, globular, spiral ; foot oval, with a trans- 

 verse furrow at its anterior edge; head wide; tentacula superior, 

 very long, conical, and pointed; eyes situated at their external 

 base, and supported upon a very apparent peduncle ; mouth ver- 

 tical, situated between two lips disposed in form of a horse shoe 

 and forming a kind of muzzle; no superior tooth ; a bristly lingual 

 band, but not prolonged into the abdominal cavity ; a very large 

 respiratory cavity, divided in two by an incomplete horizontal 

 partition. 



Animals of this genus are oviparous ; producing an eg^ nearly 

 as large as that of a pigeon, in which is found the young animal 

 complete, and in a perfectl}'^ formed shell. 



Shell. This genus appears to partake of tlie characteristics, 

 both of the Paludina and the Natica, being fluviatile and fre- 

 quently attaining a large size ; spire very short, the last whorl 

 much larger than all the others together ; globular, very ventri- 

 cose, umbilicus small, forming a compressed funnel-shaped aper- 

 ture, without interior callosity; aperture longer than broad, with 

 margins united ; columellar lip thickened, projecting and reflected 

 over the umbilicus; operculum horny. Inhabits the rivers of 

 Europe. Thirteen species. 



Ampullaria vivipara. Ampullaria rugosa. 



A. fasciata. A. canaliculata. 



10* 



