346 
COMPARATIVE ZOOLOGY. 
More than one half of all known Mammals are Rodents. 
They range from the equator to the poles, over every con¬ 
tinent, over mountains and plains, deserts and woods. The 
Fig. 387.—Beaver (Castor Canadensis). North America. 
more important representatives are the Porcupines, Capy- 
baras, Guinea-pigs, Hares, Mice, Eats, 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 w T ith ca- 
Fig. 33S. Shrew Mouse (Sorex). ^ Thej have a 
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, 
