Early Miocene; Extinct.
Original Description (from Conrad, 1840, p. 53):
"Shell profoundly elongated, ventricose, valves contracted obliquely from the apex to the middle of the basal margin; lines of growth coarse and prominent; extremity of hinge line salient and rounded; posterior extremity regularly rounded; anterior extremity rather prominent and pointed.
Locality. Cliffs of Calvert, Md. Professor Ducatel."
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