394 



MAMMALIA 



short-tailed animal with a thick body. It feeds on roots and 

 grasses and also turns its attention to young fruit trees, shocks of 

 corn, and fields of alfalfa. The pine mouse is a burrowing mam- 

 mal feeding largely underground. It is of great injury in truck 



gardens and has damaged many 

 small trees. 



Lemmings, short-tailed prai- 

 rie-dog-like forms, have a max- 

 imal production which was in 

 times past every four years, but 

 now comes about every ten 

 years. Their migrations (see p. 

 418) are a sign of over-produc- 



TI" T. ~, 'Z. ' tion. It is interesting to note 



223. Meadow mouse. (Courtesy ° 



of W. Va. Exp. Station.) that in their enemies, hares, 



Arctic foxes, weasels and lynxes, 

 there is a corresponding cycle of increase. 



The musk-rat or musquash is a small aquatic rat-like rodent 

 with a broad blunt head, thick-set body and short legs. Its long 

 tail is almost naked. Musk-rats are widely distributed through the 

 United States. They are omnivorous, feeding on the stalks and 

 roots of flags and reeds, and on animals such as insects, fish and shell 

 fish. Musk-rat skins are dyed and sold as " Hudson Seal " or 

 " electric Seal." The dormouse, a small form found in the Old 

 World, resembles a small squirrel. It spends about six months of 

 the year " wrapped in a profound sleep." It utters a shrill whistling 

 snore surprising in its volume. The American porcupines are 

 arboreal forms. They are well protected by spines which readily 

 pull out and being barbed remain in the flesh of the enemy. Jerboas 

 or jumping-mice {Dipodidae) (Figure 224 A) have kangaroo-like 

 tails and hind legs and are reputed to jump ten feet, 



TYiQ pouched gophers {Geomyidae) (Figure 224 B) are burrowing 

 rodents found in Central America and the central plains of North 

 America. The red pocket gopher is a vicious, thieving animal, 

 tremendously injurious to fruit trees, grain and vegetables. It also 

 honeycombs and weakens the banks of canals and irrigating ditches 

 m the Mississippi valley. Farmers use traps and strychnin poisoned 

 grain in an attempt to kill ofi^ the pests. 



The hare and rabbit family {Leporidae) includes two quite distinct 

 groups. The rabbit group {Sylivilagus) is represented in the United 



