Ortmann: Families and Genera oi N\i :;t;."» 



Fig. 10. Lampsilis hydiana (Lea). — Bayou Pierre, De Soto Par., La., L. S. 

 Frierson coll. Aug. 6, iqio. — Cam. Mus., Xo. 6i, 4,869. 



FlG, 11. Truncillii haysiana (Lea). — Cumberland River, Burnside, Pulaski Co., 

 Ky., B. Walker don. — Cam. Mus., No. 61, 5,001. 



Fig. 12. Truncilla florentina (Lea). — Shoals Creek, Lauderdale Co., Ala., H. 

 11. Smith coll. Nov. 2, 1909. — Cam. Mus., No. 61, 4,491. 



The scale at the bottom of the plate represents one millimeter divided into tenth?. 



