Peter;
        I'm not up on freshwater molluscs, but i do know a couple of folks who
should be able to help your contact - just ask him to give me a shout
and i'll put him in touch with them.
        I can probably be of good service to anyone wanting info regarding
marine molluscs (except Cephalopods!) from Cape Cod north, on this side
of the pond.....

Cheers,
Ross.