Bullhead, Pleurobema aesopus (Green) from Wabash River, top; Dromedary mussel, Dromus dromas (Lea), from Cumberland River, middle pair; Fan-shell, Cyprogenia irrorala (Lea), from Cumberland River, lower pair.
Freshwater and Marine Image Bank, University of Washington Libraries Digital Collections
Coker, Robert E. 1921. Fresh-water Mussels and Mussel Industries of the United States. Washington, DC : Government Printing Office. Bulletin of the United States Bureau of Fisheries, vol. 36, 1917-1918; Plate XX