Briefly summarized, the probable pre-Vashon-Wisconsin distribution of chipmunks of the species _Tamias amoenus_ in Washington was: _ludibundus_ in the higher Cascades; _affinis_ in the eastern Cascades; _canicaudus_ in eastern Washington and adjacent Idaho; and _luteiventris_ in the area north of the range of _canicaudus_. The descent of the Vashon-Wisconsin ice restricted but did not materially alter the ranges of _ludibundus_ or _affinis_. On the east, _luteiventris_ was forced southward to compete with _canicaudus_ and displaced it over a large region, especially in mountainous areas. Following the retreat of the ice, _luteiventris_, _affinis_, and _ludibundus_ extended their ranges northward over the deglaciated territory. A stock of _ludibundus_ that moved westward from Mt. Rainier became isolated and gave rise to _caurinus_. In some less obvious development, _ludibundus_ stock gave rise to _felix_ north of the Fraser River in the Cascades. TAMIAS RUFICAUDUS.--Until a better understanding of the range of this chipmunk and its relation to other _Tamias_ is gained, uncertainty will remain concerning its distribution in the past. TAMIAS TOWNSENDII.--This is a typical coastal species that ranges southward, along the coast, to California. The lowland race of western Oregon and Washington (_townsendii_) probably occurred no farther north than southwestern Washington when the Vashon Glacier was in place. Chipmunks of this species in the Cascades and in the southern Olympic Mountains probably developed independently the slightly paler color that separates _cooperi_ from _townsendii_. The tendency for species of the Pacific Coastal Fauna of the Cascades and the Olympic Mountains to be paler than their lowland relatives is widespread. After the retreat of the ice, both races probably moved northward. Perhaps because of its alpine adaptations, _cooperi_ has moved farther than _townsendii_. Also, _townsendii_, in the lowlands, ranges to the Fraser River, a barrier not encountered by _cooperi_. SCIURUS GRISEUS.--This species of the Pacific Coastal Fauna probably entered Washington from Oregon since the retreat of the Vashon Glacier. It has probably entered the state in relatively recent times.