I02 The Mammals of Colorado 
two-rooted in the adult; the outer and inner reentrant angles at the 
sides of the lower molars approximately equal in depth. 
This is a circumpolar genus being spread over the northern 
boreal portions of both hemispheres, indeed one species, E. 
rutilus, presents but one phase through this entire region 
from Scandinavia through Siberia to Arctic America. 
Some 20 American species and subspecies of this genus 
have been described, their range covering the northern half 
of the continent but extending southwards in the mountains 
to Colorado and North Carolina, and along the coasts to 
New Jersey and northern California. Only one species 
has hitherto been met with in Colorado. 
Evotomys gapperi galei (gapperi, for Gapper, an early 
naturalist; galei, for Denis Gale). Colorado 
Red-Backed Mouse. 
Evotomys galei Merriam, iV. A. Fauna, No. 4, p. 23 (1890). 
Type locality. — Ward, Boulder Co., Colorado, 9,500 feet (Denis 
Gale). 
Measurements. — Total length, 5.3 ; tail vert., 1.65 ; hind foot, 0.75. 
Description. — (From specimen taken at Lake Moraine, El Paso 
Co., Colo., altitude 10,250 feet, Aug. 29th): Dorsal stripe or area 
chestnut; sides, flanks, cheeks, nose, and feet gray; under parts 
whitish gray, plumbeous bases of hairs showing through. Tail 
bicolor, grayish white below, blackish above. A specimen from 
same locality, in winter pelage, taken Dec. iith, has dorsal area a 
somewhat lighter, brighter chestnut, and the gray of sides and other 
parts is lighter and somewhat ochraceous. 
Distribution. — This species has been reported from Colorado, 
Wyoming, and Montana. In Colorado it has been taken in the 
following counties: Boulder, Grand, Garfield, El Paso, Teller, and 
San Juan. It ranges high in the mountains, 8,000 feet being about 
as low as it is taken. It will eventually be reported from all our 
mountain counties. 
Habits. — The Red-backed Voles live in the damp woods 
and are especially fond of making their homes around and 
under dead logs. They build their nests under logs and 
