4S8 



ZOOLOGY 



especially well represented in North America. The principal 

 types are the rats and mice, many of which are close followers 

 of civilized man; squirrels, chipmunks, and prairie dogs, 

 gophers, beavers, hares and rabbits, and porcupines. Rodents 

 feed on vegetable diet, and are destructive of many plants and 

 grains which man uses for food. Notwithstanding man's 

 efforts to destroy them their remarkable power of reproduction 

 enables the more aggressive families to hold their own. Rats 



Fig. 242. 



Fig. 242. Flying Fox (Pteropus). V. S. Dept. Agriculture Year-book, i8p8. 



Questions on the figure. — What is the structure and arrangement of the wings 

 in such a form as this? To what order of mammals does this type belong? 



are among the worst of mammalian pests. They follow man 

 closely and are very destructive of certain crops and of stored 

 grains and other foods. Beside this the rats, and in less degree 

 certain other rodents, are the carriers of the bubonic plague and 

 possibly other diseases. • Fleas carry the disease from rats to 

 man. 



Order Chiroptera {hand-winged; the bats). — These are mam- 

 mals in which flight is made possible by a web or fold of the skin 



