OF THE FAMILY OF NAIADES. 425 



U. virginiana. This, doubtless, is the radiatus described 

 by Barnes. Habitat Virginia. 



U. liiteola is a variety of Say's cariosus. Habitat Susque- 

 hanna and Mohawk. 



U. marginalis. I have specimens of this species from 

 Bengal. It is w^ell characterised, although it does not alM^ays 

 possess the marginal character as described by Lamarck and 

 represented in the Ency. Meth. pi. 247. 



U. angusta. This I believe to be a variety of pidorum. 

 The figure referred to in Lister is certainly ajnclorum, and 

 is generally quoted as such. Habitat unknown. 



U. manca. This may be a distinct species, but I strongly 

 suspect it to be only a variety of pidorum. Habitat Bour- 

 gogne. 



U. eariosa is the cariosus of Say. 



U. spuria. I cannot identify this species with any of ours. 

 Habitat 



U. australis. This, like the above, is not identified. Ha- 

 bitat New Holland. 



U. anodontina. Habitat Virginia. We have no Unio of 

 this description in our waters. It is probably Jlnodonta im- 

 dulata of Say, which has sometimes small elevations some- 

 what similar to teeth*. 



U. suhorhiculata. I cannot identify this species. 



In passing criticisms upon the species of the genus Unio of 

 this great naturalist, I do not in the least wish to detract from 

 his great and merited fame. My object is expressly to en- 

 deavour to facilitate the study of this interesting genus, and 

 to remove, as far as I have it in my power, the confusion 

 which has crept into it. My observations I wish to pass 

 only for what they may prove to be worth. 



* Since writing tiie above, I observe that Sovverby on the Lamarckian Naiades 

 (Zoolog. Journ. Vol. I. p. 54.) gives the " Anodon rtigosus" of Svvainson as 

 the synonyine of U. anodontina. It is well known to our conchologists that 

 Swainson's rugosus is the old shell of Say's Anodonta undulata, which was de- 

 scribed from a young specimen, and has priority to the rugosus. 



