Early Miocene to Middle Pleistocene; Extinct.
Florida to Maryland
Original description (from Conrad, 1832):
"Suborbicular, or lentiform, a little oblique, with strong lines of growth; hinge with 2 diverging teeth in each valve; posterior tooth of the right valve bifid; anterior muscular impression not profoundly elongated.
Locality. York-town, Va. Upper Tertiary.
This species I obtained only in a very circumscribed spot, at a considerable elevation, in sand composed chiefly of comminuted shells. This calcarious sand prevails more or less in every part of the high bank at York-town, and as it is formed of shells not partially decomposed but comminuted by attrition, the fact is obvious that it has been subjected to a violent action of the waters at a period anterior to the deposition of the perfect shells it encloses, which could only have been effected in a tranquil sea."