THE MUSK-RAT. 
257 
have spread so as to threaten the sheep-raising industry, as 
they crop the herbage, leaving none for the sheep. One col- 
ony has alone lost, in 1882, 2,000,000 sheep by them. Allied 
to the hares is the social pika or little chief hare [Lagomys 
princeps), wVich abounds among loose rocks from a little 
below timber-line to the snow-line in the Kocky Mountains. 
It sits erect like a marmot, and makes squeaking, faint bleat- 
ing cries,* which appear to come from n, greater distance 
than is really the case. It resembles in shape and color the 
Guinea-pig^, and is only seven or eiglit inches long, being 
of the size of a rat. The largest of all existing rodents is the 
capybara of South America, which looks like a pig. This is 
succeeded by the slow, ugly porcupine (Fig. 315), which 
either lives in trees or burrows in the earth; it eats the bark 
and leaves of pine, larch, spruce and other trees, and the 
buds of the willow. The quills fall out at the slightest 
touch, and, lodged in the skin of a dog or wolf, are said in 
some cases to make their way into the body until they cause 
death. The porcupine makes its retreat among the roots 
of an old tree, where it sleeps much of the time. When 
distur])ed it makes a whining or mewing noise. It pairs in 
British America at the end of September, and brings forth 
two young ones in April or May. The more intelligent, 
active forms are the beaver, musk-rat, the European blind 
rat {Spalax, Fig. 296) the rats and mice, squirrels, and 
lastly the marmofs. The domestic mouse a!id the two 
rats, the brown or Norway rat {^hts dmonanus), the black 
rat {Mtts rattus), nnd the common house mouse {Mus 
mttsculus), are cosmopolitan animals. The musk-rat or 
musquash {Fiber ZihetMcus) has the hind feet partly webbed, 
so that it swims and dives welL It ranges from Florida to 
Arctic America. Northward it has three litters in the 
course of the summer, and from three to seven at a litter. 
It feeds on the roots and tender shoots of rushes and of 
* Mr. J. A. Allen says a sharp, shrill, barking cry;" but those we 
have heaxd in Colorado seem more like a faint bleat. 
