43 



referring to the numerous green lines and bands that 

 ornament its exterior surface, radiating obliquely from 

 the umbones. Within, the shell has a pearly, bluish- 

 white appearance. Length averages three inches ; 

 breadth, one and a lialf to two inches. Abundant in 

 the Vermillion, Fox, and Illinois. 



iJnio lisamoiitiuuM, Lam. A heavy, coarse shell. 

 Color brownish, rayed with green. Teeth prominent. 

 White and nacreous witliin. Length from tliree to 

 four inches. Breadth from two to two and a half 

 inches. Abundant in Illinois and Vermillion rivers. 



Unio incttineTrus, Raf. Shell heavy and thick, quad- 

 i-ate ; beaks prominent. A sinus extends down from 

 the beaks across the centre of each valve ; numerous 

 tubercles on the surface. Color j^ellowish outside, 

 white within ; teeth prominent and lieavy. Size about 

 three by three. This beautiful species is very abund- 

 ant in the Illinois river. 



Unio mititipiicaius. Lea. Shell large, tlat, brown- 

 ish without. Plications numerous. Length, six 

 inches ; breadth, four. This shell bears a strong re- 

 semblance to Unis ttndulatus^ Barnes. But I am 

 inclined to believe it to be distinct. 



Unio noTi-ei>oraci, Lea. Shell rather small and 

 Hat. Beaks not prominent, and far back. Color 

 yellowish, with interrupted, greenish lines radiating 

 from the beaks. Length, two inches ; breadth, one 

 inch. Very abundant in the Vermillion river. 



