MAMMALIA 



353 



be the smallest British quadruped, except the lesser shrews. It is 2| inches 

 long without the tail, which is the same length. The water rats, or voles, 

 represent another genus, also the meadow mice or "field mice" (Microtus) 

 (Fig. 285). The typical field mouse is a "short-eared, short-tailed, thick- 

 set" little creature 4j inches long, with a tail 1^ inches long. It is brown 

 above and white or grayish below. It is found from the Atlantic to the 

 Dakotas. It feeds on grass, roots, and grain. In severe winters they some- 

 times do much damage by eating the bark of young trees (Fig. 286). 



Dormice. The common dormouse of the Old World (Muscardi'nus avel- 

 lanarius) has a long bushy tail and looks much like a tiny squirrel. Its 

 body is "3 inches long with a tail 2- inches long." 



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Fig. 285. Carson field or meadow mouse (Microfus montanus) . (Yearbook 

 U. S. Dept. of Agriculture, 1908.) 



The American porcupines are chiefly arboreal. The quills, which are 

 but an inch or two long and are somewhat hidden among the intermingled 

 hairs, are loosely attached, so that when an animal comes in contact with 

 them they stick into it, and, being barbed, they pull out of the porcupine and 

 remain in the enemy. Hence porcupines are considered a nuisance by cattle- 

 men of the West. They are also annoying to the lumbermen of the North, 

 as they gnaw the wooden handles of their tools. These animals are so well 

 protected by their spines that they need little intelligence to escape their 

 enemies, and are rather stupid. The Old World porcupines, by some 

 authorities placed in another family, have spines a foot in length. On the 

 tail are hollow quills, which make a rattling noise somewhat like that of the 

 rattlesnake to warn the enemy. The South American genus has. a prehensile 

 tail. The little guinea-pigs are South American relatives. 



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