126 Mr. Barnes on the Genera Unio and Alasmodonta. 
projecting on the anterior basal edge; irregular profound, 
nodulous undulations radiating from the elevated ridge to 
the hinge and anterior margin. Cardinal teeth crenated ; 
lateral teeth long and striated; posterior muscular impres 
sion deep, and the anterior half of it rough. Cavity, angu- 
lar compressed, directed backward under the cardinal tooth, 
admitting the end of the finger. .Naker pearly white, with 
irregular spots of greenish, iridescent on the fore part. 
9. Unio Rugosus. Fig. 9. 
Shell broad ovate; surface wrinkled tuberculated, ribbed, 
waved; disks swelled; base falcated. 
Hab. Ohio. Mr. Collins. 
Mr. Collins’s Collection. 
Length, Breadth, 2-9 Diam. 1°5 
Shell narrowed, compressed and thin before; short, ob- 
tuse, rounded and wider behind; beaks slightly elevated; 
ligament more elevated than the beaks; hinge-margin 
compressed, carinate; basal margin falcate, emarginate, 
and compressed; anterior margin sub-angulate ; anterior 
dorsal margin sub-truncate, nearly straight; anterior, basal 
margin projecting. Epidermis dark brown, under the epi- 
dermis pearly white. Surface rough and scaly, wrinkled 
transversely and waved longitudinally, having distant irreg- 
ular transversely compressed tubercles; a broad nodulous 
elevated somewhat double ridge extending from the beaks 
to the anterior basal edge, and projecting on that part; a 
broad furrow or wave behind the ridge ending in the emar- 
ginate basal edge; and a furrow before separating the ante- 
rior lunule ; small oblique waves radiating from the ridge to 
the hinge and anterior dorsal margin. Cardinal teeth sulca- 
ted; lateral tooth striated rough and in the left valve some- 
what double: Posterior muscular impression deep an 
partly rough. Cavity of the beaks angular, compressed and 
directed backward under the cardinal tooth. Naker pearly 
white, and on the fore part iridescent. 
Remarks.—This shell agrees in some parts of its deserip- 
tion with the U. Tuberculatus. It is, however, while of the 
same length, of only a little more than half the breadth, and 
yet of longer diameter. The tubercles, also are very dif- 
ferent. In the U. Tuberculatus they are compressed /on- 
