Late Pliocene; Extinct.
Southern Florida to North Carolina.
Original Description (from Tuomey and Holmes, 1857, p. 19):
"Description. Shell sub-oval, but variable, sub-equivalve, sub-equilateral, slightly foliated, thin, margin with three or four deep plications; muscular impression large, semi-orbicular central; upper valve flat near the hinge or beaks; the two ribs in the hinge slightly divergent.
We believe this to be the first of the genus that has been found fossil in the United States. In the cabinet of Dr. Edmund Ravenel, of this State, there is a species taken from the harbour of Charleston, belonging to this genus. It is, therefore, living upon the coast of South Carolina.
Plate VI., Fig. 4. Upper valve, natural size.
" 5. Inside of lower valve, showing the costal ribs of the hinge, the muscular impression, and the perforation for the passage of the organ of attachment.
" 6. Side view of the fossil, natural size, showing the plicated margin.
Locality. Smith's, Goose Creek."
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