266 Mr. Barnes on the Genera Unio and Alasmodonta. 



versely ; surface smooth and shining. Cardinal teeth cren- 

 ulated, cavity of the beaks small ; naker bluish white, or 

 reddish yellow; surface smooth and pearly. 



Variety («) very obscurely rayed and much like Unio 

 Purpureus in shape. 



Inhabits Saratoga Lake. 



Variety (b) oval or very nearly as broad behind as be- 

 fore. 



Inhabits the Wisconsan. Capt. Douglas. 



,rt TT -xr T7" 10 \ outline of the 



18. Unio Mucronatus. Fig. 13. < , ,, 



Shell ovate, broader behind ; base compressed, fal- 

 cated ; beaks small, elevated, acute, inside pur- 

 ple. 



Inhabits the Wisconsan. Capt. Douglass. 



My collection. 



Diam. -7 Length I'S Breadth 2-3. 



Shell ovate, moderately thick, produced, narrowed, and 

 compressed before ; rounded and broad behind ; disks com- 

 pressed; anterior lunule long, distinct, with a marginal fur- 

 row; posterior lunule small, deeplyjmpressed ; hinge mar- 

 gin rounded ; basal margin arcuated ; anterior dorsal rapid- 

 ly narrowed and slightly emarginate ; epidermis horn-color, 

 and obscurely rayed ; surface smooth; cardinal teeth ser- 

 rate sulcate; cicatrices deep ; naker purplish on the mar- 

 gin, and whitish in the centre. 



Remarks." — This species has somewhat the outline of 

 the Unio Tuberculatus, but the outside is smooth. The in- 

 dividual above described is probably not more than half 

 grown, as the umbones are very little eroded. 



19. Unio Inflatus. — Shell oval, thick, tumid, 

 beaks broad, obtuse behind, wedge-shaped be- 

 fore, inside pearly white. 



Inhabits the Wisconsan and Lake Erie. Capt. Douglass. 

 Dr. Mitchill's Cabinet. 

 My collection. 



