2 6o FIRST LESSONS IN ZOOLOGY 



States, but shows some \'ariation in the different regions. 

 1 here are several species of jack-rabbits, all limited to 

 the plains and mountain regions ^\•est of the Mississippi 

 River. The food of rabbits is strictl)' vegetable, consist- 

 ing of succulent roots, branches, or leaves. Rabbits are 

 \'ery prolific, and }-earl\' rear from three to six broods of 

 from three to six )'oung each. There are two North 

 American species of porcupines — an Eastern one, Ilrctlii- 

 rjon dorsatiis, and a Western one, E. epixauthiis. The 

 quills in both these species are short, being only an inch 

 or two in length, and are barbed. In some foreign por- 

 cupines the}' are a foot long. They are loosely attached 

 in the skin, and may be readily pulled out, but the)' 

 cannot be shot out b}' the porcupine, as is popularh' 

 told. The little guinea-pigs {Ca^'ia), kept as pets, are 

 South American animals related to the porcupines. 



The pocket gophers, of which there are several species, 

 mosth' inhabiting the central plains, are rodents, found onl}' 

 in North America. They all live underground, making 

 extensive galleries and feeding chiefly on bulbous roots. 

 The mice and rats constitute a large family, of ^\•hich the 

 house-mice and rats, the various field-mice, the wood-rat 

 [Ncoloina poinsylvaiiica), and the muskrat {Filler zibet hi- 

 C7is) are familiar representatives. The common brown 

 rat {I\Ius dccumanits) was introduced into this country' 

 from Europe abcnit 1775, and has now nearly \\holh- 

 supplanted the black rat (J\I. raitiis), also a European 

 species, introduced about 1544- The bca\'er (Castor 

 canadensis) is the largest rodent. It seems to be doomed 

 to extermination through the relentless hunting of it for 

 its fur. The woodchuck or ground-hog (xirctomys nionax) 

 is another familiar rodent, larger than most members of 

 the order. The chipmunks (fig. 205) and ground-squirrels 

 are commonl)' kno«n rodents found all over the coimtr}'. 

 The)' are terrestrial members of the squirrel famii)-, the 



