160 



La vivipare a handes, Geoff. Cuvier. 



Paludina vwipara, Lam. Am'm. sans Vertehr., vol. 6, 2nd 

 part, p. VIZ. Nobis. Nichokou^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. 

 John's river, Florida, and Capt. Leconte presented me with one, 

 which he obtained at Lake Gleorge on the same river. PI. 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. 



Obs. 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 Anodnnta and Unio are 

 closely allied, yet the species were widely separated by Linn6, who 

 referred those of the present genus to Mi/tilm, whilst those of Unio 

 he associated with the Mi/x ; but an arrangement so artificial could 

 not escape BruguiSres. 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 



