Abstract:
An enigmatic fossil, Mclellania aenigma Wilson,
new subfamily (Balanidae: Mclellaniinae), genus,
and species, found embedded in the shell of the
bivalve Mercenaria, occurs in the Pliocene Croatan Formation of Lee Creek, in strata of Yorktown
age in North Carolina, Virginia, and Florida, and
in the Miocene Choptank Formation of Maryland. The enigmas are calcitic in contrast to the
aragonitic shells of Mercenaria. The pattern of
growth shows that they are produced in the living
shell and are not a result of subsequent diagenetic fossilization. Because of characters in common,
they are considered to be thoracican cirripeds,
probably parasites. A nomenclatorial revision of the principal host-Mercenaria species resurrects
Mercenaria corrugata (Lamarck, 1818).
