42 



of several species bearing a close resemblance to each 

 otlier, and is said to be distinguished from each. Loc. 

 Illinois river. 



iTnio coccincu$« Lea. A smallish species, abundant 

 in the Fox and Illinois rivers. 



Uiiio crn>isi<icn!^, Lam. A rather thick, large species, 

 of a greenish color ; abundant in Illinois river. 



iJnio eics-au.««. Lea. A small, short species, richly- 

 colored. Illinois river. 



Lnio eiiii>!«i!«, Lka. Shell Very oblique ; rather 

 heavy. Color brownish, white within, teeth promi- 

 nent. About two and a half inches in diameter. 

 Abundant in Fox and Illinois rivers. 



Unio ebcnits. Lea. A heavy black-colored shell, 

 common in the Illinois river. 



Unio g-raciiiw, Baunes. Tliis species is rather fragile 

 and very plain in appearance. Loc. Illinois river. 



Unio gibboiinis, Barnes. A very plain, coarse shell, 

 Color dark brown ; very gibbous. Within, color 

 bluish. Loc. Illinois, Fox, and Vermillion rivers. 



Uno iris. Lea. A rather flat shell, obliquely rayed 

 with greenish bands. Length, two and a half inches. 

 Loc. Illinois river. Not abundant. 



Unio lutcoius. Lam. A variable shell, some being 

 quite flat while others have an inflated appearance. 

 The name indicates the characteristic of the shell, 



