Miocene to Early Pleistocene; extinct.
Florida to Virginia.
Original description (from Conrad, 1834):
"Shell subtriangular, compressed, with numerous concentric rounded costae, crowded on the basal margin; umbones slightly flattened; apex acute, central; lunule large, concave, lanceolate; posterior margin concave; submargin acutely angular, straight; extremity obtusely rounded; cardinal teeth strongly striated; margin crenulated. Length, one inch and one-eighth; height, seven-eighths of an inch.
Locality. Yorktown, Va."
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