La vivipare a handes^ G-eoff. Cuvier. 
Paludina vivvpara^ Lam. Anim. sans Yertehr.^ vol. 6, 2nd 
party p.Ylo. JVbhis. Nicholsou’s Enc. 
Ohs. This appears to be one of the many species^ that are com- 
mon to North America and Europe. And though the specimens 
from the two continents differ a little^ yet this difference is so 
slight as not to be specific. Cuvier remarks that ^^the female 
produces living young, which are found in its oviducts, in the 
spring, in every state of development. Spallanzani assures us, 
that the young, taken at the moment of their birth and nourished 
separately, reproduce without fecundation, like those of the Aphis. 
The males are nearly as common as the females ; their generative 
organ is exserted and retracted, as in Helix, by a hole pierced in 
the right tentaculum, which causes this tentaculum to appear 
larger than the other. By this character the male is easily 
known.^^ 
The vivipara is far less common than the decisa, and seems to 
be more usually found in the southern part of the Union. Mr. 
Elliott of Charleston sent me two specimens from the banks of St. 
J ohn’s river, Florida, and Capt. Leconte presented me with one, 
which he obtained at Lake Greorge on the same river. PL 10; 
the two middle figures exhibit the brownish banded var. 
[Am. Con. vol. ii. April, 1831.] 
Anodonta. — Shell equivalve, inequilateral, transverse, regular ; 
hinge margin linear, without teeth having a sinus before ; ligament 
external, elongated, terminating in the anterior sinus ] muscular 
impressions two, remote, posterior one compound. 
Ohs. These are shells of rather large size, residing in fresh water 
streams and lakes. They are generally perlaceous within and green- 
ish on the exterior. Although the genera Anodonta and Unio are 
closely allied, yet the species were widely separated by Linne, who 
referred those of the present genus to Mytilus, whilst those of Unio 
he associated with the Myse ; but an arrangement so artificial could 
not escape Bruguieres. He perceived their affinities, and grouped 
them under the above mentioned denominations. Several other 
allied genera have been formed by subsequent naturalists, distin- 
guished from the present by the existence of either cardinal or 
