Art's question on just how we tell very similar taxa from each other is
a valid one: so, what we need is a book or arcticle-series which
summarizes the conchological differerences between taxa - OR, a "Key to
the Recent Genera of Molluscs" - now i know Ruth Turner has done a nice
conchological key for NE North America, but has anyone done one for a
larger, more diverse area??
-Ross.