Late Pliocene to Middle Pleistocene; Extinct.
Southern Florida to Virginia.
Original Description (from Say, 1824, p. 142):
"Suborbicular, with about twenty-five convex ribs, and wrinkled across; inner margin crenate.
Description. Beaks nearly central, a little prominent, curved backward: ribs granulated on the umbones, and transversely wrinkled near the base, convex: apices somewhat prominent beyond the general curve of the shell: inner margin and edge crenate: cardinal teeth two.
Length from the apex to the base four-fifths of an inch, breadth nearly the same.
Rather proportionally longer than the decussata, and more oblique."
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