CHAPTER VIII 



Order V. Rodcntia 

 (Gnawing Animals) 



THE Rodents are small or moderately sized animals, 

 many of which in their external appearance strongly 

 resemble some of the Insectivora. They are more widely 

 distributed than any other order of the Mammalia ; except 

 in the extreme Polar regions they are found everywhere, 

 although Australia, especially considering its size, is poorly 

 represented. There are quite a thousand species, some of 

 which are marked by their countless myriads of individuals ; 

 and in this respect it is fortunate for mankind that most of 

 them are ' Wee, sleekit, cowerin', tim'rous beasties.' Never- 

 theless they have very diverse habits. They are among the 

 swiftest of the Mammalia, they are diggers and delvers in 

 the earth, they are flying gymnasts, they are expert divers, 

 or they are agile leapers whose movements the eye can 

 scarcely follow. 



The word ' Rodent' literally means a gnawer, and is given 

 to the animals on account of the structure of their teeth. 

 Of grinders they are usually furnished with at least three 

 above and below on each side. Canine teeth are altogether 

 absent. They all possess two incisors in each jaw, which 

 occupy more than half the space ; in a very few species 

 there is a pair of small or rudimentary incisors in the upper 

 jaw. The number of grinders may differ, but the incisors 

 are always widely separated from them. Their outer 

 surface is faced with enamel, which wears more slowly than 

 the softer inner side of the tooth, so as always to present a 



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