>. One other
> question then if you don't mind, Being that the "pleurotomaria" are a rather fragile group are
> many fossil specimens found
> that are somewhat complete? Are these fossils  found mainly in shale?

The local fossil pleurotomariids are in limestone.  The shells have dissolved away, leaving internal
and external molds.  Pieces of internal molds are much more common than relatively complete internal
molds, and I only have a few external molds.  The "external" mold of the umbilicus is rather
peculiar, especially if you find one broken off from the rest of the mold.  It looks a bit like the
central column of the Paleozoic bryozoan Archimedes.  Other fossils may be in a variety of rock
types.  In general, the preservation should be similar to that of other mollusks in the deposit.
Thus, the Paris Basin Eocene Chelotia may occur in almost pristine condition, apart from loss of
color and operculum, in calcareous sand, whereas the Eocene pleurotomariids from New Jersey are
squashed molds that often fall apart soon after collection, which is part of why no one has studied
them since the late 1800's.

Dr. David Campbell
UNC-CH Geological Sciences
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