io6 The Mammals of Colorado 
the State of Sonora. In addition to the widely distributed 
type species several other forms have recently been recognized. 
Fiber zibethicus (from Lat. zibetum, the odorous substance 
of the zibet, or civet, in allusion to the musk 
secreted by the animal). Muskrat. 
Castor zibethicus Linn., Syst. Nat., 12th ed., i., p. 79 (1766). 
Type locality. — Eastern Canada. 
Measurements. — Total length, 22 ; tail vert., 9.5 ; hind foot, 3.1. 
Description. — (From a specimen taken at Crested Butte, Oct. 
1 6th): The pelage consists of a short, close under fur, brown in 
color, with long outer guard hairs, dark brown in color; feet dark 
brown; under parts pale grayish, with longer pale brown hairs scat- 
tered through the under fur on belly, but nearly wanting on chin 
and throat; blackish spot on chin. 
Distribution. — The Muskrat is found over entire North America, 
north of the southern boundary of the United States. In Colorado 
it may be said to occur in every county where there is enough 
permanent water for it to swim in, and ranges up to 10,000 feet or 
more elevation. 
Habits. — Muskrats are of semi-aquatic habits and con- 
sequently are always found about water. Their dense close 
fur is adapted to the aquatic life, and the flattened tail is an 
excellent rudder when swimming. They live in holes in the 
banks of the streams and ponds, and also build houses of mud 
and grass similar to those of the beaver, but of course smaller, 
but the animal has never been known to construct dams. 
Its food is largely grass, and such other vegetable matter 
as it can procure. In some regions it brings the freshwater 
mussels up from the bottom and by biting the hinge between 
the two valves opens the shell and devours the contents. 
Piles of these shells may be seen where the animal has been 
feasting. It will also eat other animal food. One was seen in 
a lake near Crested Butte chasing under water a "Water 
Dog," Ambly stoma tigrinum, which it finally captured by 
making a sudden dash forward and seizing it with its teeth. 
The rat then came to the surface with its prey in its mouth, and 
