144 University of California Publications in Zoology. [VoL 
Peromyscus sonoriensis sonoriensis (leConte). 
Sonora White-footed Mouse. 
We found Peromyscus s. sonoriensis to be the most wide- 
spread mouse of the region. Its range appeared to be coincident 
with that of the sage (Artemisia tridentata), except that we 
found the mouse sparingly at higher elevations, well through the 
Transition zone. We trapped the species June 28 and 29, 1905, 
at 8500 feet altitude at the margins of the cienaga at the head- 
waters of the south fork of the Santa Ana; and a very few were 
taken in the vicinity of Bluff lake, 7500 feet altitude, in July 
and again the first of September. These were the highest stations 
zonally for this species. We found it abundant in the sage flats 
along the upper Santa Ana from a little above Seven Oaks, 5100 
feet altitude, to the mouth of Fish creek, 6500 feet. At three 
of our camps the mice came into our grub tent, and continuous 
trapping was necessary to keep them from doing damage. Fully 
thirty-five were trapped in our tent at the mouth of the South 
Fork, in 1906. It was surprising how soon the httle animals 
would start in housekeeping. Large globular nests, of cotton and 
bits of paper, would appear in our boxes overnight. 
We found the species common in the sage on the margin of 
Bear lake, the first of August, 1905. It was also taken in August 
at Saragossa springs, and at Doble, 6800 to 7500 feet altitude; 
and they were abundant in the tract of sage at the north base of 
Sugarloaf. But we failed to find them farther over towards the 
desert. 
In the series of eighty-six specimens secured there is a great 
amount of variation shown, much of it due to age apparently. 
This form is very closely related to P. s. gambeli which is so 
common in the Pacifie coastal slope of southern California. But 
the San Bernardino mountain form, sonoriensis, is appreciably 
paler-colored and slightly larger than gambeli. The Mojave 
desert form deserticola seems to me most similar, in fact iden- 
tical as far as external characters are concerned. However, I 
forwarded three San Bernardino mountain specimens to Mr. W. 
H. Osgood, who marked them sonoriensis, and I accept his deter- 
mination. 
