88 
wide and prominent; beaks slightly elevated; epider- 
mis brown olive, with angular spots disposed in form 
of rays; cardinal teeth direct; subpyramidal, promr 
nent; within white; cavity capacious. 
OBSERVATION S. 
This shell is distantly related to U. ovatus, Say, 
but is more elongated, less ventricose, and has inter" 
rupted rays; the epidermis posteriorly has numerous 
short vermicular raised lines. I found the species 
only on the bank of Elk river, near its junction with 
the Tennessee at the Muscle shoals. 
UNIO RUBELLU8, 
Plate VI. — Fig. 2. 
DESCRIPTION. 
Shell suborbicular, ventricose, thick; beaks sub- 
central; umbones prominent; umbonial slope rounded, 
margined before by a faint angle; a similar angle be- 
hind the umbonial slope; beaks eroded, slightly pro- 
minent; epidermis reddish brown; cardinal teeth di- 
rect; muscular impressions small and distinct; nacre 
pink or purplish. 
OBSERVATIONS. 
A small species, which I obtained only in the Black 
Warrior, near its source, among the mountains of 
Alabama; it is rather an obscure species, but I can- 
