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



Plati^ XXIL 



?!?wf !1^ """"^ middle right: Piiik heel-splitter, LamPsilis alata (Say), from I^Hssissinpi River fSee o , , ^ 



Lower left and lower right: White heel-sphtter, Symphynota complanata (Barnes) from Kankaki?Rive?f ' (See p. ,,.) 



