48 



Specimens of tliis shell, brought from the Lakes and their vicin- 

 ity, by Mr. Lesueur, had the revolving lines very obscure or obso- 

 lete. 



Lister's lower figure of tab. 109 also resembles tliis shell. 



Paludina vivipara.* — Shell subconic, with six rounded 

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

 brown bands, of which the middle one is generally smallest ; whorls 

 of the spire with but two, aperture suborbicular, more than half 

 the length of the shell. Plate 2, fig. 3. 



Donov. Brit. Shells, tab. 87, Helix vivipara. 



Lister. ConcJi. tab. 126, Jig. 26; Cochlese vivipara fasdata. 



It is doubtful whether or not this is the same as the vivipara, 

 but it certainly approaches very near to it; we, however, refer it to 

 that species until a specific diflPerence 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. 



Paludina dissimilis. — Shell conic, dark horn color or black- 

 ish ; whorls about three, with obsolete, distant wrinkles, and an 

 abrupt, acute, prominent carinated line, which revolves on the mid- 

 dle of the body whorl, and is concealed on the spire by the suture; 

 suture not indented, aperture oval, half as long as the shell, within 

 sanguineous beneath the carina, and at base and apex ; columella 

 emarginated, a little flattened at the base. Length about two-fifths 

 of an inch. 



Var. a. Carina obsolete on the ventral portion of the body 

 whorl. 



Var. 6. Carina distinct on the spiral whorls, owing to their more 

 oblique revolution. 



The surface of the whorls of the spires is generally covered with 

 inequal calcareous matter, resembling a fortuitous accumulation of 

 mud or earth on that part, but which appears to be superposed by 

 the animal, probably with the intention of retaining a proper specific 

 gravity. The apex is often tnuicated. 



This species was found by Mr. Thomas Nuttall, during a journey 

 to Pittsburg. 



*[In the earlier editions of Nich. Enc. this species was described under 

 Lymnaea. — Ed.] 



