SOREX PALUSTRIS.--This species has a wide range in North America and extends southward in the Cascade-Sierra Nevada Chain to southern California. Its extensive range at present in this mountain chain suggests that it was resident in the Cascades previous to Wisconsin time. Mountain water shrews probably reached the Olympic Mountains from the Cascades by way of the Puget Bridge in early Recent Time. SOREX BENDIRII.--This Pacific Coastal species probably had a history very similar to that of _Neurotrichus_ and _Scapanus orarius_. The difference between the Bendire water shrews of western Washington and western Oregon indicates that the Washington population was separated from the shrews of western Oregon during Vashon Time. The white-bellied race of the Olympic Peninsula is probably of local origin. MICROSOREX HOYI.--The Washington record of this shrew at Loon Lake, Stevens County, is in an area where mammals typical of the Rocky Mountain Fauna occur. MYOTIS LUCIFUGUS.--The dark race of this species (_alascensis_) may have persisted through the glacial period in southwestern Washington. The race _carissima_, of the Great Basin Fauna, may have entered the state since the glacial period, from the south, of course. Habitat selection determines their range at present. MYOTIS YUMANENSIS.--The dark, coastal race (_saturatus_) seems to be an established member of the Pacific Coastal Fauna. Unlike _lucifugus_, the coastal race is not found east of the Cascades. The race _sociabilis_, of the Great Basin, has doubtless entered the desert of eastern Washington from eastern Oregon. MYOTIS KEENII.--The southernmost record station for this north coastal species is on the Olympic Peninsula of Washington. It probably developed in the humid, northern part of the Pacific Coastal area previous to the last Pleistocene glaciation and extended its range to the south in Vashon-Wisconsin Time. The range of tolerance in _M. k. keenii_ seems to be more restricted than that of _M. lucifugus alascensis_. MYOTIS EVOTIS.--In Washington, the distribution of this bat is similar to that of _Myotis lucifugus_. The dark, forest race probably originated in the north-coastal region. The paler race, that developed in the southwest, entered eastern Washington from Oregon. MYOTIS THYSANODES.--In Washington this species has been recorded only in the southeastern part where the Great Basin Fauna occurs. It probably originated in the southwestern United States, and a point in British Columbia a little way north of Washington marks the northern edge of its natural range. MYOTIS VOLANS and MYOTIS CALIFORNICUS.--Remarks made about _Myotis lucifugus_ apply also to these two species. MYOTIS SUBULATUS.--The northwestern periphery of the range of this species seems to be in eastern Washington. LASIONYCTERIS NOCTIVAGANS.--Undifferentiated subspecifically from coast to coast, no basis is provided for judging the route by which this species entered the state.