MURIDE 471 
fur, interspered with longer stiff, glistening hairs, which overlie and 
conceal the former on the upper surface and sides of the body. 
The general colour is dark umber-brown, almost black on the back 
and gray below. The tail and naked parts of the feet are black. 
The musky odour from which it derives its name is due to the 
secretion of a large gland situated in the inguinal region, and present 
in both sexes. 
The Musk-Rat is peculiar to America, being extensively distri- 
buted in suitable localities in the northern part of the continent, 
extending from the Atlantic to the Pacific, and from the Rio Grande 
Fia. 209.—The Musk-Rat (Fiber zibethicus.) 
to the barren grounds bordering the Arctic Seas. It is aquatic in 
its habits, living on the shores of lakes and rivers, swimming and 
diving with great facility, feeding on the roots, stems, and leaves of 
water-plants, or on fruits and vegetables which grow near the 
margin of the streams it inhabits. Musk-Rats are most active at 
night, spending the greater part of the day concealed in their 
burrows dug out of the bank, consisting of a chamber with numerous 
passages, all of which open under the surface of the water. For 
winter quarters they build more elaborate houses of conical or 
dome-like form, composed of sedges, grasses, and similar materials 
plastered together with mud. As their fur is an important article 
of commerce, large numbers are annually killed, being either trapped 
or speared at the mouths of their holes. 
The skull of the Musk-Rat is shown in Fig. 203 (p. 459) ; its 
structure is essentially Arvicoline, but the squamosals are greatly 
