VIVIPARA. 13 



and have not the facilities for observing the 

 animal in action, can satisfy themselves by a 

 comparison of Haldeman's figure of Paludina 

 decisa at rest (Plate I, fig. 1) with Mr. Bin- 

 ney's figures above cited. 



Thus, then, I divide Vivipara : 



* Whorls regularly rounded, generally banded, 

 texture thin, umbilicate. typical. 



Inhabits all parts of the world. The Ameri- 

 can species very evidently belonging to the 

 European group. 



** Whorls flattened around their upper por- 

 tions, generally without bands, solid, 

 nearly or quite imperforate. 

 A group peculiar to North America. 



f Smooth. Subgenus Melaniho. 



ff Nodulous. " Tuloioma. 



The following species belong to each group ; 

 those described by Haldeman being in Roman 

 type, spaced, and the species characterized 

 more recently in italic : 



Vivipara, inter text a, Say, v i v i p a- 

 [39] 



