Monograph of the Fresh-Water Univalve Mollusca 
of the United States. 
Family VIVIPARIDZ, H. and A. Adams. 
GENERA. 
* Operculum concentric. 
Vivipara, Montfort.* 
** Operculum concentric, with spiral nucleus. 
LiopLax, Troschel. 
Genus VIVIPA RA, Monéfort. 
(For description of shell and animal see 
Haldeman, Paludina, p. 1.) 
In the year 1862 I proposed to divide this 
genus into several subgenera, and these have 
* Lamarck’s Vivépare, 1809, cannot be quoted because 
not Latinized. Montfort published in 1810. 
[37] an 
