2l6 ANIMAL BIOLOGY 



The order Insectivora includes mostly small animals 

 which (as the name implies) feed mainly upon insects. 

 The best known forms are the moles and shrews. The 

 moles are characterized by their soft fur, small eyes and 

 ears and powerful fore legs with broad hands and strong 

 claws fitted for digging in the earth. Moles spend nearly 

 all their life underground, where they make long burrows, 

 occasionally throwing up mounds of earth, or "mole 

 hills," above their chief habitations. The shrews are 

 small mouse-like animals which lead a very active and 

 mostly underground life in search of insects, snails and 

 earthworms. The European hedgehog has its back cov- 

 ered with a coat of spines, much like the porcupines which 

 belong to a quite different order of mammals, and are 

 often improperly termed hedgehogs in this country. 



The order Rodentia, or gnawers, is a very large group of 

 mostly small mammals including the rats, mice, squirrels, 

 gophers, and numerous others. Canine teeth are lacking 

 in the rodents, and the incisors are chisel-like and capable 

 of continuous growth so as to compensate for the wear that 

 results from their frequent use. The rodents are largely 

 vegetable feeders, consequently many species are very 

 destructive. Some of the worst offenders are the common 

 domestic mouse and the house rat, both of which were 

 introduced into this country from Europe. The rat, in 

 addition to its depredations upon grain and all sorts of 

 stored food, is an important agent in the spread of the 

 plague, as has already been described in treating of 

 the flea which may carry this dangerous disease from rats to 

 man. Among the largest of the rodents are the porcu- 

 pines. The American species ranges over a considerable 

 part of North America. Among the most valuable and 

 interesting of the rodents are the beavers which have 

 been much sought for on account of the value of their fur. 



