190 Merriam The Chipmunks of the Genus Eutamias. 



squirrels of the subgenus or genus Ictidomys Allen, and Eutamias 

 from those of the subgenus or genus Ammospermophilus Merriam. 

 The substance of the present preliminary paper may be con 

 veniently arranged under the following headings : 



1 . General remarks on distribution. 



2. Seasonal changes in pelage. 



3. List of species and subspecies. 



4. Remarks on the townsendi group (with keys}. 



5. Remarks on the speciosus group. 



6. Note on Tamias quadrimaculatus Gray. 



7. Desci'iptions of new species and subspecies. 



1. GENERAL REMARKS ON DISTRIBUTION. 



There are no Chipmunks in the Sonoran deserts of the western 

 United States, but the vast sage-brush plains of the central and 

 northern parts of the Great Basin are inhabited by a small gray 

 ish species (Eutamias pictus), and other species live in the higher 

 mountain ranges. On reaching the eastern base of the Sierra 

 Nevada in California, and of the Cascade range in Oregon and 

 Washington, one enters the region where the genus Eutamias 

 attains its highest development. Excepting the great interior 

 valley of California and one or two small valleys in southwestern 

 Oregon, which are not inhabited by any Chipmunks, the strip 

 of territory included between the east base of the Cascade-Sierra 

 system and the Pacific Ocean may be said to be fairly overrun 

 by these animals, containing not less than 14 species and sub 

 species. The chaparral-covered hills of southern California and 

 the lower slopes of the mountains that surround the Mohave 

 Desert and the great San Joaquin Valley have only a single 

 species ; but the boreal forests that clothe the higher mountains 

 and practically the whole of western Oregon and Washington 

 are the homes of a large number of forms belonging to three or 

 four distinct groups. In the forests west of the Cascade Mts. 

 only a single species occurs (E. townsendi), except along the ex 

 treme southwestern coast of Oregon, where it is replaced by an 

 allied form (E. ochrogenys). On the eastern slopes and higher 

 parts of the Cascade Mts. two species are found together the 

 small E. amoenus, which extends southward on the Sierra Nevada 

 to about latitude 37, and the large E. townsendi, which inhabits 

 the Cascades from British Columbia southward to a point between 



