TEE MUSK-RAT. 257 



have spread so as to threaten the sheep-raising industry, as 

 they crop the herbage, leaving none for the slieep. One col- 

 ony has alone lost, in 1883, 2,000,000 sheep by tliem. Allied 

 to the hares is the social pika or little chief hare {Lagomys 

 princeps), which abounds among loose rocks from a little 

 below timber-line to the snow-line in the Rocky Mountains. 

 It sits erect like amarmot, and makes squeaking, faint bleat- 

 ing cries,* which appear to come from a greater distance 

 tlian is really the case. It resembles in shape and color the 

 Guinea-pig, and is only seven or eight inches- long, being 

 of tlie size of a rat. The largest of all existing rodents is the 

 capybara of South America, which looks like a ]iig. Tliis is 

 succeeded by the slow, ugly porcupine (Fig. 315), which 

 either lives in trees or burrows in the earth; it oats 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 tlie roots 

 of an old tree, where it sleeps much of the time. Wlien 

 disturbed it makes a whining or mewing noise. It ])airs in 

 British America at the end of Septembei-, and brings forth 

 two young ones in April or May. The more intelb'gent, 

 active forms are the beaver, musk-r:it, the European blind 

 rat {Spalax, Fig. 296) tlie rats and mice, squirrels, and 

 lastly the marmots. Tlie domestic mouse and the two 

 rats, the brown or IS'orway rat {Mus dccnmanus), the black 

 rat [Mus irittus), and the common house mouse {3fiis 

 musculus), are cosmopolitan animals. The musk-rat or 

 musquash [Fiber Zibefhicus) has the hind feetpartly webbed, 

 so that it swims and dives well. It ranges from Florida to 

 Arctic America. ISTorthward 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 ruslies and of 



* Mr. J. A. Allen says " a sharp, sliiill, Imrking cry;" but those we 

 have beard in Colorado seem wore like a faint bleat. 



