Dear Hoosier;-
        Pilsbry is certainly the one to get for land snails. But the two
volumes weigh about 25 lbs. and the cost will be considerable.
        There's a damn good book on fresh water mussels of Illinois by Paul
Parmalee that will be most helpful. It is soft cover and can be
purchased from the Ill. State Museum. Pop. Sci. Series vol.8,
Springfield, Ill. It works for Ohio and Kentucky shells 95% of the time
and should work for Indiana.  And it wont cost more than about $10.00.
        Art