Early Miocene; Extinct.
Original Description (from Dall, 1900, p. 1086):
"Oligocene of the Chipola marl, Calhoun County, Florida; Dall and Burns.
Shell small, solid, strong, rounded, subovate, with about thirty-eight rather close-set ribs, with narrower channelled interspaces; the anterior ribs to the number of about fourteen exhibit the strung and flattened cup-imbrication like Cardium consors in miniature; the posterior fourteen are asymmetrical, with an undulate or irregularly twisted serrate keel on the anterior side of the rib; those in the middle of the disk have a similar keel on the posterior side of the rib; the outer posterior ribs are more or less muricate or spinulose, and the posterior margin is serrate, the rest merely fluted internally; exceptionally perfect small specimens show small and extremely delicate spines on the medial ribs. Alt. 27, Ion. 25.5, diam. 18 mm.
The delicacy and fragility of the ornamentation of this little shell are such that not a single specimen of many preserved its sculpture intact."
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