36 VIVIPARA. 



No. 8854 of the Smithsonian collection, was labelled Pal. Georgi- 

 ana by Mr. Lea. 



Fig. 64. Paludina Georgiana, Lea — Shell ventricose-couical, 



thin, dark horn-colored, smooth ; sutures very much 

 impressed ; whirls about five ; convex ; aperture nearly 

 round, white. 



Hopeton, near Darien, Ga. Prof. Shepard ; my cabi- 

 net ; cabinet of Prof. Shepard. Diameter .7, length 

 1.1 inch. 



This species in form resembles most, perhaps, the 



P. vivipara. It is not quite so large, nor has it 



bands. It is rather more elevated, and the body 



Paludina Georgiana. whirl is smaller and rounder than the P. decisa, Say. 



The aperture at the base recedes more than is usual 



with the genus. (^Lea.) 



Of Pal. lineata the following is the original description : — 



Paludina lineata, Valenciennes — This species resembles that of the 

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

 ovate, thin, diaphanous, with delicate transverse strise ; greenish horn- 

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

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

 shell. Besides the striag 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. Apex 

 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 

 fnll 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 this, while the Mollusca furnish more numerous ones. 



Length 1 inch 3 lines. (^Valenciennes.) 



§ 4. Shell simple. 



b. Globose. 



ViTipara intertexta, Sat — Shell subglobose, yellowish-green or 

 brownish, wrinkled, and with minute, very numerous, obsolete revolving, 

 deciduous lines ; spire depressed conic, obtuse, truncated, eroded at tip ; 



