We thank Jim Baugh for freely sharing information on habitat and distribution of mollusks in the Cascade Mountains. We are especially grateful to John T. Longino and The Evergreen State College for providing temporary workspace and for allowing us to use the Syncroscopy Auotomontage System for digital image capture that was used to create most of the photographs that appear in this key. This work was supported by National Science Foundation grants DEB-0072702 and DBI-0215820 to John T. Longino and colleagues.