Bull. U. vS. B. F., 1917-18. 



Plate IX. 



Upper pair: Flat niggerhead, Quadrula coccinea (Conrad), from Fox River. (See p. 25.) 

 At liottom: Wabash piti-toe, Quadrula rubigmosa (Lea), from Cedar Creek, Ind. (See p. 25.) 



