346 COMPARATIVE ZOOLOGY. 



More than one half of all known Mammals are Eodents. 

 They range from the equator to the poles, over every con- 

 tinent, over mountains and plains, deserts and woods. The 



FIG. 337. Beaver (Castor Canadensis). North America. 



more important representatives are the Porcupines, Capy- 

 baras, Guinea-pigs, Hares, Mice, Rats, Squirrels, and Bea- 

 vers. The Capybara and Beaver are the giants of the 

 race. 



5. Insectivora are diminutive, insect -eating animals, 

 some, as the Shrew, being the smallest of Mammals. 



They have small, smooth brains, 

 which, as in the preceding orders, 

 leave uncovered the cerebellum 

 and olfactory lobes. The molar 

 teeth bristle with sharp, pointed 

 cusps, and are associated with ca- 



F M .838.-Shrew Mouse (Sam). n j nefl and incigors Thej haye fl 



long muzzle, short legs, and clavicles. The feet are formed 

 for walking or grasping, and are plantigrade, five-toed, and 

 clawed. The Shrew, Hedgehog, and Mole are examples. 



6. Cheiroptera, or Bats, repeat the chief characters of 

 the Insectivores ; but some (as the Flying-fox) are fruit- 

 eaters, and have corresponding modifications of the teeth. 

 They are distinguished by their very long fore -limbs. 



