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SPECIES IX. Unio lavigata (Elliptio lavigata.} 



Shell elliptical, rounded, ventricose, thick, 

 smooth ; epidermis olive ; nacre bluish white ; 

 cardinal tooth slightly wrinkled ; lamellar tooth 

 short. Length % diam. f axis T 7 F of the 

 breadth. 



A small species, at most an inch in breadth; it 

 approaches the genera Rotundaria and Cyclas. 

 Found in the Kentucky river. .Apices rounded, 

 prominent, and eroded ; lamellar tooth somewhat 

 oblique. This species ought perhaps to belong 

 to the sub-genus Plagiola, of the genus Obli- 

 quaria. 



SPECIES X. Unio zonalis (Elliptio zonalis.} 



Shell elliptical, thick, wrinkled; epidermis red- 

 dish with brown zones ; apices prominent, ven- 

 tricose. Length f diam. f axis f of the 

 breadth. 



This species is rare, found but one specimen 

 at the falls of the Ohio ; breadth upwards of two 

 inches. 



Fourth Sub-genus EURINEA. 



Valves very transversal or broad ; axis almost 

 lateral ; ligament very long. 



