Here is a reference that discusses introduced molluscan taxa in Western
North America.  theba is mentioned.  This paper discusses terrestrial,
freshwater and marine introduced taxa.

G. Dallas Hanna. 1966. Introduced Mollusks of Western North America.
Occasional Papers of the California Academy of Sciences. No. 48, 108
pages, 85 figures and 4 plates.

Also, from the Australian literature I had a photocopy of an article
discribing the infestation of a marina in Darwin, Northern territories,
Australia.  The marina was infested with Mytilopsis sallei and the way
they eradicated it was by killing off all life in the marina area with
pesticides! Actually "120 tonnes of chlorine and 2.5 tonnes of copper
sulphates for Cullen Bay Marina alone."  Let us keep examples like this in
mind when we think about exchanging live specimens.  I do not have the
actual reference for this paper but could get it if anyone wants the
reference.  It is from 2000.  Perhaps someone from Australia can shed some
light on this incident.

Regards,
Charlie
******************************************************************************
Charlie Sturm, Jr
Research Associate - Section of Invertebrate Zoology
                     Carnegie Museum of Natural History, Pittsburgh, PA
Assistant Professor - Family Medicine

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