OF THE CLASS MAMMALIA. 



277 



galleries under ground, in which they dwell. Molehills are 

 formed of the product of these excavations. They seldom 

 quit their excavations, and live on insects and worms. De- 

 stined to live in profound dark- 

 ness, their eyes are scarcely 

 perceptible, and there is a 

 species of the mole which is 

 completely blind. The mole 

 has twenty-two teeth in each 

 jaw, or forty-four in all. The 

 common mole of the fields, of 

 a fine black colour, is common 

 throughout the fertile coun- 

 tries of Europe. 



418. The order rodentia comprises the ordinary ungui- 

 culated mammals which have no canine teeth, but have strong 

 chisel-shaped teeth in front, or incisive, and molar teeth behind. 

 This arrangement of the teeth (Fig. 243) adapts them for 

 gnawing very hard vegetable substances, as the bark and 

 roots of trees, and these in fact form their principal nourish- 

 ment. The brain of rodents resembles greatly that of the 

 insectivora, and their intelligence is very confined ; neverthe- 



Fig. 240. Shrew Mouse 

 (Musaraigne). 





less, some are gifted with extraordinary instincts. Squirrels 

 (Fig. 118), marmots, rats, hamsters (Fig. 119), the campagnol 

 (Fig. 242), the porcupine (Fig. 195), and several other animals 

 similarly organized, belong to the order rodentia. 



Kodents of the genus Mus are characterized by some pecu- 



