Characters previously mentioned in the literature as having
taxonomic worth for supraspecific categories of chipmunks were
checked by me on specimens old enough to have worn permanent
premolars. Some structural features not previously used were
found to have taxonomic significance. The baculum in each of
the supraspecific categories of sciurids of North America was
examined; the bacula were processed by the method described by
White (1951:125) to obviate "variation" caused by shriveling of
the smaller bacula or breaking of the more delicate parts of
the larger bacula. Mallei and hyoid bones of the genera and
subgenera of the chipmunks were mostly studied in the dry
state. Part of the hyoid musculature in these same groups of
chipmunks was dissected.
In all, I studied more than 1,000 skulls and skins of the
subgenus _Neotamias_, approximately 50 skulls and skins of
_Tamias striatus_, and 15 skulls and skins of the subgenus
_Eutamias_ (_Eutamias sibiricus asiaticus_ from Manchuria).
Numerous other specimens were examined but not in such detail.
I am grateful to Professor E. Raymond Hall for guidance in
the study. For encouragement and advice I am grateful also
to Doctors Robert W. Wilson, Cecil G. Lalicker, Edwin C.
Galbreath, Keith R. Kelson, E. Lendell Cockrum, Olin L. Webb,
and others at the Museum of Natural History, and in the
Department of Zoology of the University of Kansas. My wife,
Alice M. White, made the drawings and helped me in many other
ways. For lending specimens I thank Dr. David H. Johnson of the
United States National Museum, and Dr. George C. Rinker of the
Department of Anatomy, University of Michigan.
Assistance with field work is acknowledged from the Kansas
University Endowment Association, the National Science
Foundation, and the United States Navy, Office of Naval
Research, through contract No. NR161 791.