Animals of the Mississippi Bottoms near Qiiincy. 151 



This small mollusk was common in many o£ the pools, but 

 was not often brought out in the nets from pools in which it 

 was very abundant. The shell is about .20 inch in diameter 

 and may be recognized at once among our species by the strong 

 ridges on the outside of the shell. It is somewhat depressed 

 and the aperture is nearly circular in outline. The food is 

 said to be vegetable matter. The eggs of related European 

 species are deposited singly. 



Family Viviparid.^. (River Snails.) 



Vivipara infertexta, Say. 



(Paludina intertexta, Say, New Harmony Disseminator, ii, 



244, 1829.) 



A common and uniformly distributed snail of rather large 

 size. Shell rather stout, with about five strongly convex 

 whorls. Adults dull reddish brown in color; young paler, with 

 numerous fine revolving strias on the whorls. The largest 

 example taken measures one inch in length, with the largest 

 whorl .87 inch in diameter. Inside the aperture may usually 

 be seen several large reddish brown revolving bands. The 

 young are born alive. 



Localities: Harkness Slough, Willow Slough, Lily Lake, 

 Long Lake, Wood Slough. 

 Vivipara suhpiirpurea^ Say. 



{Paludina suhpurpurea^ New Harmony Disseminator, ii, 



245, 1829.) 



Found only in Lily Lake. It is much like the preceding, 

 but has a slightly more tapering shell with the whorls flattened 

 next the revolving suture. 

 Canipeloma decisum, Say. 



{Lim}uca decisa, Say, Am. ed. Nich. Enc. 1, 1817.) 

 This was the largest and most abundant river snail ob- 

 served. It may be distinguished from the two preceding by its 

 more slender form, more tapering spire, and less convex whorls. 

 The general color is a uniform olive green, more or less stained 

 towards the apex with brown. Inside the aperture pure bluish 

 white. An example measures 1.37 inches in length, with the 

 largest whorl .87 inch in diameter. The young are brought 



