BULLETIN FLORIDA STATE MUSEUM


 C D
 lmm
FIGURE 2.-Marstonia lustrica (Pilsbry): (A, B) Riverine form; Cedar Swamp, nr. Urbana, Cham-
paigne Co., Ohio (UF 22223); (C) Lacustrine form; Hess Lake, Newaygo Co., Michigan (UF
22190); (D) Extremely slender lacustrine form; Turkeyfoot Lake, Summit Co., Ohio (UF 22225).


Vol. 21, No. 3