19 



name, but his description (in which from his own 

 admission he blends several species) is worth no- 

 thing. The shell is thicker in this, than in the 

 preceding species ; otherwise it resembles it very 

 much; the principal difference consists in the 

 axis being more lateral, and the want of posterior 

 inclination. Breadth from four to five inches. 



SPECIES III. Unio viridis (Elliptic viridis.} 



Shell elliptical, obliquely truncated posterior- 

 ly ; slightly ventricose ; scarcely thick ; apices 

 with flexuous wrinkles ; epidermis smooth, olive 

 green ; nacre bluish ; cardinal tooth compressed, 

 crenulated, divergent. Length | Diam. -^ 

 axis i of the breadth. 



Var. 1. radiata radiated with pale yellow. 



Var. Z.fuscata epidermis brownish olive. 



A small species, at most an inch and an half in 

 breadth, rare in the Ohio, common in the Kentucky 

 and the small rivers adjacent. Apices seldom 

 eroded, for they are thickened by flexuous folds 

 or wrinkles, remarkable because the rest of the 

 exterior is smooth. The cardinal tooth is slender, 

 and, in consequence, becomes crenulated instead 

 of being furrowed ; truncation oblique, convex ; 

 muscular impressions slight ; no fossule ; lamellar 

 tooth slender. 



