34 VIVIPARA. 



cies. The spire is also almost double the length of that of suhpurpurea, 

 aud the epidermis of a lighter color. (^Tryon). 



Vivipara incrassata, Lea — Shell smooth, elliptical, rather thin, 

 imperforate, dark horn color; sutures somewhat impressed ; whirls some- 

 what convex ; columella thickened above ; aperture rather round, small, 

 within bluish. 

 Fig. 58. Alabama. E. Foreman, M. D. Cabinet of Dr. Foreman. 



Diam. .52, length . . . inch. 



Rather more than the first whirl only of the specimen 

 before me is perfect, and I would not have proposed it for a 

 new species, but that this part differs from any which has 

 come under my notice. The callus on the superior part of 

 the columella is very like that we find in the genus Ancu- 

 Paludinain- losa. The aperture is smaller than usual in this genus. 

 crassata. fi^e upper whirls being decollate, neither their number nor 

 the form of the spire can be given. (Lea.) 



Pahidina incrassaia, Lea, Tr, Am. Phil. Soc. IX, 30 (1844); Obs. iv, 30. 

 Proc. ii, 283 (1842), 



The figure given above (fig. 58) is taken from Mr. Lea's origi- 

 nal specimen. I have not seen others. 



Palildina Tivipara, Say — Shell subconic, with six rounded 

 whirls ; suture impressed, color olivaceous or pale, with three red-brown 

 bands, of which the middle one is generally smallest, whirls of the spire 

 with but two ; aperture suborbicular, more than half the length of the shell. 



It is doubtful whether or not this is the same as the vivipara, but it.cer- 

 tainly approaches very near to it ; we, however, refer it to that species 

 until a specific difierence can be indicated, which at present we are unable 

 to do ; the spire of this species is rather more obtuse, and the suture not 

 so deeply impressed, as in the figures of the European specimens above 

 mentioned. 



Doxov. Brit. Shells, tab. Ixxxvii, Helix vivipara. — Listek, Conch, tab. 

 cxxvi, fig. 26 ; Cochlea vivipara fasciata. 



This appears to be one of the many species that are common to North 

 America and Europe. And though the specimens from the two continents 

 differ a little, yet this difference is so slight as not to be specific. Cuvier 

 remarks that " the female produces living young, which are found in its 

 oviducts, in the spring, in every state of development. Spallanzani assures 

 us, that the young, taken at the moment of their birth and nourished 

 separately, reproduce without fecundation, like those of the Aphis. The 

 males are nearly as common as the females ; their generative organ is ex- 

 serted and retracted, as in Helix, by a hole pierced in the right teutaculum, 



