68 



Unio altilis, 



Conrad, 



* There is so great a difference in the colour of the epider- 

 mis in a variety of this shell, that it may be considered dis- 

 tinct by some Conchologists. The specimen described by Rafi- 

 NESQUE had a yellow epidermis, that of Barnes was black. I 

 found both varieties in the streams of the Tennesee Valley, in 

 Alabama. 



t Mr. Lea gives canwafus, of Barnes, among the synonymes of 

 this species, but it is very distinct. It is \\iq fasciata, of Rafi- 



NESQUE. 



