768 PLEUROBEMA 
I have never seen what | felt certain was a specimen of this 
species and am at a loss to know just where to place it. Conrad 
states that “the young shell is broader behind, approaching to 
an oval figure, and is prettily ornamented with green rays on 
an olive-yellow ground.” His figure in the New Fresh Water 
Shells is considerably different from the one in the American 
Journal of Science, but the former may be from a younger 
shell. The high broadly rounded, mammillar beaks, placed at 
some distance from the anterior end and the rather decided 
angle behind the ligament are distinguishing characters. 
PLEUROBEMA NUCLEOPSIS (Conrad). 
Shell short elliptical, subinflated, solid, inequilateral; beaks 
moderately full and high; posterior ridge scarcely developed, 
widely rounded ; anterior end almost evenly rounded; base and 
dorsum curved : posterior end rounded ; surface nearly smooth ; 
the rest marks a little depressed; epidermis tawny or tawny- 
brown with a row of small green spots on the posterior ridge 
in the young shell, dirty brown in the old state; pseudocardi- 
nals triangular; laterals short, stout, that of the right valve 
partly double; muscle scars small; beak cavities shallow ; nacre 
bluish-white. 
Length 30, height 24.5, diam. 15 mm. 
Length 46, height 39.5, diam. 24 mm. 
Coosa River system. 
Type locality, Etowah River, Ga. 
Unio nucleopsis Conrap, Ann. and Mag. Nat. Hist., IV, 1840, 
p 2013: JL Ac Nw Sci Phila, 1) 850, p..276, pease ee 
8r.— Kusrer, Conch. (Cab, Unio, 1801) piety) piaenmen tie 
fig. 3. Reeve, Conch. Icon., XVI, 1864, pl. xv1, fig. 68. 
Margaron (Unio) nucleopsis Lua, Syn., 1852, p. 35; 1870, Pp. 
56. 
Pleurobema nucleopsis SIMPSON, Syn., 1900, p. 755. 
Conrad’s figure is evidently taken from a young shell and 
shows it to be almost evenly short elliptical. A specimen in 
the Lea collection about the size of Conrad’s figure, bearing 
the name Unio nucleopsis Conrad, agrees very well with the 
figure of that species but is somewhat broken behind. Lea 
