Aue: N@erius. 
VoL. VIII. MARCH, 1895. No. 11 
UNIO OCHRACEUS AND CARIOSUS. 
BY CHARLES TORKEY SIMPSON. 
The senior editor of the Nautitus has asked me to point out in 
a clear concise way the specific differences between Unio ochraceus 
Say, and] Unio cariosus Say. They were both described in Nichol- 
son’s Encyclopedia, in an article on conchology, by Say; and the 
work, which is now long out of print, is exceedingly rare, and out 
of the reach of the ordinary student. 
Union oehraeensSay. — 
Both belong to a great assembly of North American forms fairly 
typified by the well known Unio occidens, it being one of the few 
groups that are well represented both in the Mississippi Valley and 
