Doug, Thanks for the backup.  I'll send you that $5. next week.

Zoogeography, one of my favorite subjects.  I deal with land snails, but
since we'll probably end up discussing plate tectonics, marine mollusks
will be involved by default because they get dragged around on the "plate"
margins...

Walter Miller and Edna Naranjo-Garcia published in 1991 (American
Malacological Bulletin, 8(2):147-153) probably one of the most
thought-provoking papers of the century, at least for land snails.  They
reviewed information on the lost paleo-continent of Pacifica, which
wandered around in the Pacific realm, broke apart and through some
pangenesis (sort of my own usage of the word, but steeped in definitional
fact) the pieces floated to points beyond and accreted onto the continental
margins of Asia, South America and North America.  This breakup occurred in
the Mesozoic and the resultant meanderings and accretions probably took
another few millions of years.  Of course, Pacifica must of had snails on
it and other mollusks around it and these little boogers got carried along
and dispatched wherever the land mass 'stopped'.  One large piece slipped
through the seaway between North and South America (the Isthmus of Panama
did not come into existance until a short 3 or so million years ago).  This
piece makes up some of the Greater Antilles, etc, the Caribbean Plate in
general.  As far as marine mollusks go......wouldn't it be interesting if
one could correlate the arrival of this chunk of real estate with the
arrival of the, what is now, the "Caribbean" fauna, after the demise of all
the taxa with Tethyan affinities at the end of the Eocene, just a few
million years later?  This Pacifica theory (backed with substantial
geophysical data) (NOT JUST THE CARIBBEAN PIECE) explains a lot of weird
land snail distributions, i.e. the apparent close relationships of the
Caribbean xanthonychids with the western helminthoglyptids and
humboldtianids, the South American epiphragmophorids and all of the above
with the Asiatic Bradybaenidae.  Also, the presence of the clausiliid
group, Nenininae, in South America and so on.  It explains away necessary
extinctions which could not be proven.  Groups wouldn't have had to have
been in the New World as long as when it was thought these originated from
a Gonwanan connection. They arrived later, much later.

Scratch your heads over this during the weekend.  It's fun to think about.
Kurt