392 BULLETIN 56, UNITED STATES NATIONAL MUSEUM, 



Type-locality. — Altitude of 9,000 foot on San Francisco Mountain, 

 Arizona. (Type, skin and skull, Cat. No. Utit, U. S. National 

 Museum.) 



Geographical range. — Transition and Boreal zones of the mountains 

 of the Elevated Central Tract. 



When, in 1889, at the suggestion of Dr. J. A. Allen, I undertook the 

 rearrangement of the American Museum specimens of the short -tailod 

 wood mice and plains mice of the West, which were then known col- 

 lectively as Hesperomys leucopus sonoriensis, I restricted the applica- 

 tion of Le Conte's name sonoriensis to that one of the five forms rep- 

 resented in the specimens examined which came from the place geo- 

 graphically nearest to the typo-locality of sonoriensis, viz., to the 

 species inhabiting the mountains of central Arizona, the typo locality 

 of Le Conte's Hesperomys sonoriensis being the Mexican town of Santa 

 Cruz, just south of the Arizona border, in Sonora. Immediately fol- 

 lowing this, Dr. C. Hart Merriam a redescribed the mouse to which I 

 had restricted the name sonoriensis and named it Hesperomys leuco- 

 pus rufinus, although at the time quite as ignorant as nvyself concern- 

 ing the identity of Le Conte's Hesperomys sonorit nsis: and, indeed, it 

 was not until the year 1893, when I visited Santa Cruz, Sonora (the 

 type-locality), and collected a series of topotvpes of sonoriensis, and 

 afterwards compared them with the type-specimen (skin and skull of a 

 young individual) in the U. S. National Museum, that anyone knew 

 the characters of Le Conte's animal, and that it was a geographic 

 (zonal) race distinct from the Arizona wood mouse (Peromyscus sono- 

 riensis rufinus) , to which Doctor Merriam was fortunate enough to have 

 pinned a name that sticks. On account of its supposed resemblance 

 to the eastern wood mouse, Peromyscus leucopus (Rafmesque), Doctor 

 Merriam named it as a subspecies of that mouse without showing that 

 it intergrades or has any connection of range with that species. In 

 the absence of proof it is unsafe to assume either of these to be a fact, 

 and at present the pronounced cranial and external characters of P< / - 

 omyscus sonoriensis seem to warrant its separation as a distinct 

 species, as it is not known to intergrade with any other. 



Description. — Similar in color to Peromyscus leucopus (Rafmesque), 

 but slightly smaller, with much larger and broader ears, shorter tail, 

 and lanuginous tufts at anterior base of ears. In winter the color 

 above is brownish fulvous, mixed with black in the median line; ears 

 dusky with hoary edging; tail sharply bicolor, with the stripe along 

 its upper surface narrow and dusky; feet and under parts white. In 

 summer the color of the upper surface is tawny cinnamon. Length, 

 160 mm. ; tail vertebra?, 68 (to end of pencil, 73) ; ear above crown, 15 

 (above notch, 19); length of hind foot, 20; skull, 26 by 14. 



u North American Fauna, No. 3, 1890, p. (14. 



