75 
VIVIPARA*, De Montfort. 
Gen. Cuar. Univalve, ovate or oblong, with a 
regularly elevated rounded spire. Aperture 
entire, oblong, longitudinal, the two lips 
united angularly above. 
EE 
Tue term Helix being by late Authors confined to those 
shells only which resemble Helix promatia of Linn., 
we are willing to adopt the generic name Vivipara of 
Montfort, for such as are like Helix Vivipara of Linn., 
although it may imply a character that, perhaps will not 
be found in every shell otherwise not generically different. 
The recent prototype of this genus, being a fresh water 
shell, analogy would lead us to suppose the fossil shells 
nearly resembling it to have been inhabitants of fresh water 
also, which have long been supposed not to have been 
preserved, but under such circumstances as may be ex- 
plained, as Mr. Parkinson says, ‘‘ on the supposition of 
their having been involved in the gradually accreting 
tufaceous matter which is deposited by streams and rivers, 
or in the stalactitical concretions forming the cavities of 
Limestone rocks of comparatively modern formation.’ 
Org. Rem. v. 3, p. 86. Those in the tufaceous substance 
might happen to be the remains of dead shells, even of the 
current year, and are often of the same species as those living 
in the rivers or lakes where the deposit has taken place. At 
* We believe the shells here described belong to Lamarck’s genus Bu- 
limus, but they do not exactly agree in several characters, and moreover the 
exact. prototype of this genus is undoubtedly a fresh water, and not a land 
shell, as Lamarck’s Bulimi are. 
