17 
south as Erie, the number of species which also 
occur in the Tennessee is considerably increased; 
amongst these are Unio rectus of Lamarck, U. acu- 
tissimus, Lea, U. teres, Rar. U. plicatus, Say, U. 
reflexus, Rar. U. verrucosus, Rar. and U, undatus, 
BARNES. 
Unio interruptus, Say, does not inhabit the Black 
Warrior, and is rare in the Alabama above Clai- 
borne; six miles below this village, it is very abun- 
dant on an extensive bar. 
U. stapes, Lua, inhabits both these rivers, and has 
as yet been found in no other; it is extremely rare. 
Unio arcus, nobis, I have found only in the Ala- 
bama. 
Unio acutissimus, Lea, is very rare in the rivers 
abovementioned, but is abundant in Flint river, a 
tributary of the Tennessee. 
Unio decisus, Lea, has been confounded with WU. 
scalenius, Rar. but is very distinct. It has, as yet, 
been found only in the Black Warrior and Alabama 
rivers; in the latter very abundantly. 
Unio Alabamensis, nob. The observations on 
B2 
