Early Miocene; Extinct.
Original Description (from Dall, 1900, p. 1098):
"Oligocene of Alum Bluff and the Chipola beds of the Chipola River, Florida, Burns; and of Roberts, Escambia County, Alabama, E. A. Smith.
Shell thin, polished, with large, full beaks; subequilateral, rounded in front and below, obliquely subtruncate behind; sculptured with about twenty-four strong ribs, of which the anterior five or six are smooth, thence to the middle of the shell with thickened adherent scale-like ornaments (which I call lepidote for short) especially near the margin, the remainder of the ribs smooth, except on their sides, where they are cross-striated, as are the narrow channelled interspaces; posterior area smooth with obsolete radial grooves, one or two near the hinge stronger; no pseudolunule; hinge normal, strong; internal margins sharply fluted, sulci reaching well up on the disk. Lon. 34, alt. 36, diam. 24 mm.
This shell in its general characters is a miniature Cardium robustum, and is especially characteristic of the Chipola horizon."
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