THE RODENTS OR "GNAWING" ANIMALS 31 



of Russia, and later the rest of Europe. They appear to have 

 reached Paris about 1750. 



It is a more omnivorous feeder than the black rat, and more 

 easily adapts itself to varied conditions, thriving in the dwellings 

 and sewers of great cities, no less than in farm-buildings and on the 

 banks of rivers. It is a bold and fierce animal, and will not scruple 

 to attack even human beings when " cornered." 



Mice and rats, like rabbits, are nocturnal animals, and this 

 because, being defenceless, they are subjected to fewer enemies 

 and have better chances of escape by night than by day. But 

 cats, owls and foxes levy heavy toll on them nevertheless. By 

 day, however, they would have far more foes to contend with. 



The selected types of rodents which we have just briefly 

 surveyed, it should be remarked, acquired their structural peculi- 

 arities as they became more and more perfectly adapted to their 

 special methods of feeding. From the small size of these creatures, 

 nuts, roots, and so on could not be taken whole into the mouth 

 and ground up by the crushing teeth, as with the larger vegetable 

 feeders ; and this same diminutiveness compelled them to adopt 

 stealthy habits to avoid enemies. By way of contrast, then, 

 attention should now be turned to the giants, relatively speaking, 

 among the vegetable feeders. And of these the horse and the ox 

 may well serve as types. 



