Both the genus and species are from Say, 1820 so all references should be to Exogyra costata rather than Ostrea, etc.

The deposits with Exogyra in the Carolinas are also the source of the Cucullaea internal molds.  Although Cucullaea did survive into the Paleocene in the eastern U.S., the deposits for the Myrtle Beach material are Maastichtian (uppermost Cretaceous) and thus closer to 70 than 60 million.  Incidentally, this also illustrates a caution of beach collecting, especially when the beach has been renourished.  All sorts of fossils may be present!  Cretaceous molds are relatively obvious, but Pleistocene shells may not be obviously different from the Recent material.

    Dr. David Campbell
    "Old Seashells"
    Biology Department
    Saint Mary's College of Maryland
    18952 E. Fisher Road
    St. Mary's City, MD  20686-3001 USA
    [log in to unmask], 301 862-0372 Fax: 301 862-0996
"Mollusks murmured 'Morning!'.  And salmon chanted 'Evening!'."-Frank Muir, Oh My Word!