2G LAND AND FRESH-WATER SHELLS OF X. A. PART IIL 



DoNor. Brit. Shells, tab. Ixxxvii, Helix vtvipara. — Listek, Conch., tab. 

 cxxvi, fig. 26 ; Cochlea vivipara fasciuta, &c. &c. 



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 diflFerence is so slight as not 

 Fig. 48. ^Q ]jQ specific. Cuvier remarks that " the female 



produces living young, which are found in its ovi- 

 ducts, 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 exserted and re- 

 tracted, as in Helix, by a hole pierced in the right 

 tentaculum, which causes this tentaculum to appear 

 Paludma vivipara. larger than the other. By this character the male 



is easily known." 

 The vivipara is far less common than the decisa, and seems to be more 

 usually found in the southern part of the Union. Mr. Elliott of Charleston 

 sent me two specimens from the banks of St. John's River, Florida, and 

 Capt. Leconte presented me with one, which he obtained at Lake George 

 on the same river. PI. 10,' the two middle figures exhibit the brownish 

 banded var. (Say.') 



The next notice of the species was by Eaton, in 1826, who 

 describes it as Helix vivipa7'a. 



In 1841 it is again described and figured by Haldeman, as 

 identical with the European Paludina vivipara. The bands are 

 spoken of as "several." Prof. Haldeman quotes Pal. lineata in 

 the synonymy. (See that species). 



The description of DeKay (1843) gives no additional informa- 

 tion regarding the species, wliich is " extra-limital" to New York ; 

 it gives only four whirls and three bands to tlie shell. 



In 1852, in the second edition of Cliemnitz, this species is de- 

 scribed and figured as Paludina linear'is. 



In tlie Proceedings of the Philadelphia Academy, 18C2, p. 451, 

 Mr. Tryon points out the fact of the American shell being in- 

 variably distinguished by the presence of four bands, yet refers it 

 to Pal. lineata, Yal., which derives its name from its being some- 

 times characterized by numerous revolving lines of green color 

 instead of bands. 



' One of the figures is given in my figure 48. 



