Middle-Late Miocene to Late Pleistocene; Extinct.
Panama to North Carolina.
Note that Middle Pleistocene map point for species in northern Florida is in error and will be corrected in the future.
Original Description (from Say, 1832, p. 36):
"Shell rather thin, transversely oblong; ribs about forty, somewhat flattened and much broader than the intervening spaces which are very narrow, and with a longitudinal impressed line, particularly on those of the posterior margin, which are almost bifid; and with numerous slightly elevated transverse lines, which being divided by the longitudinal striae appear granulated: beak but little prominent, and nearly opposite to the posterior third of the length of the hinge margin: area narrow and elongated: hinge margin rectilinear, angulated at each extremity; teeth numerous, small; posterior margin obliquely rounded inwards, no part of it extending further backward than the angle: anterior margin obliquely truncate: inner margin crenate.
OBSERVATIONS. A fossil shell from the same locality as the preceding, and also sent to me by Mr. Elliott.
REFERENCE TO THE PLATE. Fig. 1, Exterior and Interior views. Pl. 36"
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