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338 New species of Fresh Water Shells. 
Art. Ix. —Description of some New Species of Fresh Water Shells 
_ from Alabama, Tennessee, &c.; by Timoruy A. Conran, Mem- 
ber of the Academy of Natural Sciences of Philadelphia. 
Unio cenatus. Pl. 1. fig. De 
‘Shell sub-triangular ; ; much compressed, surface waved and vith 
small irregular undulations becoming profound towards the posterior . 
margin; anterior side and umbo destitute of undulations; umbones 
flattened ; beaks prominent. 
sTabebits ‘Tennessee, Elk and Flint rivers, ands is rare. “liek 
1.8 inches. Cabinet of the Academy of saat Sciences of Phil- 
-adelphia. 
Shell ‘sub-triangular; very inequilateral, and much compressed, 
with a broad furrow extending from the beaks to the base; an- 
terior sides and umbo entire, and the remaining parts furnished vorith 
small irregular ‘interrupted undulations, which are profound behind 
‘the umbonial slope; surface rough, with distant slight concentric 
grooves ; umbones much flattened; beaks prominent, compressed ; 
epidermis dark olive, and obscurely rayed; cardinal and lateral teeth 
very robust; anterior and posterior muscular i a —? 
nacre pearly white and iridescent. 
Observations. This is a remarkable end very distinct species; 
very similar in outline to the U. securis‘of Lea; but differing from 
all its congeners in the singular‘manner in which its undulations or 
“incipient tubercles are disposed ; itis nearly as much compressed as 
the U. securis. The epidermis in some specimens is almost’black, 
Unto PEROVATUS. Pl. 1. fig. ss 
Shell ovate, ventricose, valves cdederstely thick; beaks jatar 
prominent, cardinal teeth erect; lateral teeth robuilinensy compress- 
ed; nacre white. 
‘Inhabits Prairie creek, Moareuzo Co. Al. rare ; Length 1.9 Hitlies. 
Cabinet of the Academy of Natural Sciences af Philadelphia. - 
Shell ovate, rather ventricose, valves thick on the anterior side, 
but becoming much thinner on the posterior ; anterior margin regu- 
larly rounded ; basal margin rounded; posterior extremity subangu- 
lated; beaks a little elevated, approximate and undulated at tip; 
eidotnnis olive, and wrinkled towards the margin; cardinal teeth 
erect and prominent, not very thick; lateral teeth rectilinear, com- 
