120 Mr. Barnes on the Genera Unio and Alasmodonia. 
Maj.. Delafield’s collection. 
Diam. 1°7 Length, 23 Breadth, 3:1 
Remark.—This shell is thinner than specimens of the 
same size usually are. =. 
2. Unio Undulatus. Fig. 2. ; Hero 
Shell rhombick ovate, with numerous waving folds radia- 
ting from the beaks. 
Unio Peruviana ? M. Lamarck. 
Taken by Mr. Collins in the Ohio and preserved in his 
—— 
1°9 Length, 34 Breadth, 
Shell hick, very short and obtusely we ‘behind 
beaks slightly elevated; hinge-margin sub-alated, compress- 
ed, carinated, distinct with a furrow on each side ; anterior 
dorsal margin sub-truncate; Epidermis blackish brown ; ; 
surface finely wrinkled transversely ; wrinkles becoming 
meet on we anterior side ; oblique folds deeply indent- 
the anterior margin ; waves largest and deepest below, 
Ba eapeoning Pe the anterior dorsal margin, fine, numerous, 
curved upwards, and extending to the ligament above ; 
longitudinal poset extending from the beaks to the an- 
terior dorsal margin; decussating the oblique waves; the 
lowest furrow deepest, the other somewhat obsolete ; disks 
tuberculated below the beaks. Cardinal teeth sulcated ; 
posterior cicatrix very rough and deep; Naker pearly white, 
irregularly spotted with brownish green. 
Remark,—A large and very beautiful shell. ra 
. : ‘ a. inside. 
3. Umi Plicatus. Fig. 3 <4 5 gasaide; 
Shell sub- “radrepesiar, tumid, sinuous before with dis- 
ae ne olds ; hinge-margin elevated, compressed, car- 
Unio plicata. Le Sueur. Mr. Say. 
Unio Rariplicata. M. Lama vr a 
Hab. Ohio, Mississippi, and Daienidin. 
