Mountain Weasel 
197 
clear dark brown, decidedly darker on head; tail the same, some- 
what lighter beneath, and with black tip ; upper lip and chin white ; 
rest of under parts buff with a decided orange tint ; upper surface of 
front feet and hind toes, and inner side hind legs yellow ; soles of 
hind feet pale brown. According to Merriam the color of the under 
parts varies quite considerably in depth and shade. 
The winter pelage is white with black tip to tail. Many specimens 
show a yellow tinge on the under parts, and a January specimen 
from Salida is decidedly yellow underneath and on the flanks, 
and the tail has a strong brownish yellow suffusion. 
In spring and autumn specimens are found showing the various 
stages of transition between the two pelages and are often very 
interesting. 
The skull is proportionally smaller than that of P. longicauda, 
and the brain case decidedly less triangular, owing to the postorbital 
region being less constricted. The zygomata are not wide spreading 
and not markedly arched. The lambdoidal and sagittal crests 
are not specially prominent ; the skull is narrower across mastoids 
and the parietals bulge out decidedly. Bullae seemingly somewhat 
smaller. 
P. arizonensis may be distinguished from P. longicauda by its 
decidedly smaller size, darker color above, and by the cranial 
differences noted above. 
Distribution. — The Mountain Weasel is found from Arizona and 
New Mexico north through the Rocky Mountains and Sierra 
Nevadas, reaching British Columbia in the Rocky Mountains, but 
in the Cascades and Sierra Nevadas is not found north of the 
Siskiyou Mountains. 
In Colorado it is found well distributed through the mountains, 
and onto the west edge of the plains; it is recorded from Colorado 
Springs, and Lake Moraine, El Paso County; from Fort Colhns, 
Larimer County; Coventry, Montrose County; Crested Butte, and 
Sapinero, Gunnison County; Salida, Chaffee County; and from 
Boulder County. It has a range in elevation from six to above 
eleven thousand feet. 
Habits. — The habits of this species do not differ essentially 
from those of other weasels. They live more in the moun- 
tains and foot-hills than the Long-tailed Weasel, but their 
prey is much the same. 
Putorius streatori leptus (streatori, for C. P. Streator; 
Grk. leptos, thin, fine, delicate). Dwarf Weasel. 
