30 



LAND AND FRESH- WATER SHELLS OF N. A. PART III. 



acute, from below the middle to the base slightly curved. Leugth 9'", 

 breadth 7'". 



East Florida, in Lake Ware (Rugel). Coll. Charpentier (Shuttleworth). 



The lingual membrane of Vivipara georgiana is figured below. 



Fig. 57. 



Lingual membrane of Vivipara georgiana. [Stimpson.] 



Tivipara lineata, Valenciennes — This species resembles that of 

 the Seine. It is equally ventricose, but has a thinner shell. Shell ventri- 

 cose-ovate, thin, diaphanous, with delicate transverse strije ; greenish horn- 

 color, with numerous transverse greener vittse. Whirls five, last one 

 large, ventricose, and equalling in height one-half the entire length of the 

 shell. Besides the striae of growth, there are numerous transverse, very 

 fine lines. The whirls are not flattened towards the moderate suture. 

 Apex acute. Color green, sometimes somewhat corneous ground, on which 

 are a large number of bands of a deeper green and variable width, some- 

 times merely linear. On the upper whirls the bands are obsolete. Apei 

 not eroded in any of a large number of individuals. 



Operculum brown, thin, horny, covered with numerous concentric, not 

 spiral, lines. Found in Lake Erie by M. A. Michaud, who found one shell 

 full of young, as in the case of our species, which proves the species to be 

 viviparous. There is reason to believe the other species also are so, though 

 in the most natural genera species vary in being both oviparous and vivi- 

 parous. The genera of colubers and vipers among the reptiles are an 

 example of tliis, while the Mollusca furnish more numerous oues. 



Length 1 inch 3 lines. (^Valenciennes.) 



