666 UNIO 
Under this name, Unio icterinus, | have united a number of 
nominal species, none of which possess any very striking char- 
acters. In general the form is oblong, elliptical or subrhom- 
boid, and not much inflated; the shell is solid; the epidermis 
smooth, shining, and some shade of tawny color. It is a more 
solid species than errans and it has a different texture and 
color from twomeyi, being more waxy. 
UNIO CUVIERIANUS Lea. 
Shell elongated, elliptic rhomboid, subinflated or convex, 
solid, inequilateral; beaks slightly elevated; posterior ridge 
prominent, subangulate above, becoming somewhat double be- 
low, ending above the base in a faint biangulation; surface 
with irregular, concentric sculpture, more or less smooth and 
shining; epidermis tawny-brownish, sometimes tinged with 
green; pseudocardinals double in each valve, the anterior one 
of the right valve smali, the others stumpy; laterals curved; 
muscle scars large, impressed; nacre white or purplish, rather 
dull. 
Length too, height 57, diam. 36 mm. 
Type locality, Washington County, Georgia. 
Unio cuvierianus Lea, Tr. Am. Phil. Soc., [X, 1852, p. 263, 
plo xvE fie.-165 Obs:, V5 18525 py 10) plo xvi; fie TO: 
Margaron (Umo) cuvierianus Lea, Syn., 1852, p. 32; 1870, 
posi: 
Unio icterinus (part) SIMPSON, Syn., 1900, p. 727. 
In the Synopsis I placed this in the synonymy of U. tcter- 
imus Conrad, and it approaches that species quite closely. Re- 
cent study has, however, led me to believe that it may be dis- 
tinct. It is somewhat more elliptical than Conrad’s shell, is 
more inflated and generally rather less elongated. 
UNIO ROANOKENSIS Lea. 
Shell large, elongated, subrhomboid or sometimes subobo- 
vate, compressed or subcompressed, inequilateral, subsolid or 
solid; beaks low, subcompressed, their sculpture apparently a 
few longitudinal corrugations; posterior ridge moderately de- 
