PLEUROBEMA 745 
erals two in the left valve and a somewhat double one in the 
right; beak cavities not deep; muscle scars well impressed ; 
nacre white, thicker in front. 
Length 61, height 40, diam. 24 mm. 
Length 58, height 35, diam. 18 mm. 
Type locality, Kentucky ; Tennessee. 
imo tesievi Lea, Pr. Ac. N. Sci. Phila., 1V,. 1860, p. 306; Jl. 
AcwN. oc rila;, TVe tooo, p:.352, pl. tvit, fig. 17753 Obs., 
VTL, 1860, p: 34, pl.Lvint, fig: 177. 
Margaron (Unio) lesleyi Lea, Syn., 1870, p. 40. 
Pleurobema les!eyi StIMPSON, Syn., 1900, p. 748. 
Approaches cuneolus, but is more elongated, rather more 
nearly elliptical and has perhaps more regular pseudocardinals. 
I have heretofore remarked that the figure of Unio patulus 
seems nearer to this than anything else. 
PLEUROBEMA OVIFORME (Conrad). 
Shell irregularly ovate or subrhomboid, scarcely subinflated, 
rather solid; beaks high, not very full, turned forward over a 
well-developed lunule, their sculpture a number of broken, sub- 
nodulous ridges: posterior ridge moderate, narrowly rounded, 
ending just below the median line in a point; outline of the 
dorsal slope curved, much elevated and subangular near the 
middle; base line rounded; anterior end rounded; epidermis 
with fine, concentric folds, nearly smooth on the earlier growth, 
tawny, greenish-yellow or yellow-green, with narrow and 
broad broken rays; pseudocardinals uneven, two in the left 
valve, one with vestiges of two others in the right; laterals 
two in the left valve, a double one in the right; beak cavities 
rather shallow ; muscle scars deep, small; nacre silvery-white. 
Length 46, height 33, diam. 20 mm. 
Type locality, Tennessee. 
Unio oviformts Conrap, New F. W. Shells, 1834, p. 46, pl. 1, 
fig. 6.—CHENu, Bib. Conch., tst ser., III, 1845, p. 22, pl. 
a. Ss 7. 
Margaron (Unie) oviformis Lra, Syn., 1852, p. 26; 1870, p. 40 
Pleurobema oviformis Simpson, Syn., 1900, p. 748. 
