Color descriptions are based on Ridgway's Color Standards and Color
Nomenclature published in 1912.

[Footnote 1: References in parentheses are to the Bibliography, p.
40 (the last figure being to the page of the publication).
References to authorities where no citation of literature is
appended relate for the most part to manuscript notes in the files
of the Biological Survey or the University of Arizona Agricultural
Experiment Station.]

[Footnote 2: In addition to assistance rendered by officials of the
Biological Survey and the University of Arizona, which is hereby
acknowledged, the authors are indebted to the following persons for
helpful suggestions and assistance: G. S. Miller and J. W. Gidley,
of the U. S. National Museum; Dr. Frederic E. Clements and Gorm
Loftfield, of the Carnegie Institution; Morgan Hebard, of the
Academy of Natural Sciences of Philadelphia; James T. Jardine and
R. L. Hensel, both formerly connected with the U. S. Forest Service;
and R. R. Hill, of the Forest Service. They are also indebted to
William Nicholson, of Continental, Ariz., for many courtesies
extended in connection with work on the Reserve.]




IDENTIFICATION.


There are only three groups of mammals in the Southwest having external