234 ANIMAL FORMS 
dogs, ground-squirrels, and chipmunks of the terrestrial 
species are of frequent occurrence, and of the tree-dwellers 
the fox, gray and red squirrels are well known in many 
sections of the United States. 
219. Insect-eating mammals (Insectivora).—The shrews 
and moles belonging to this order are representatives of a 
large group of small animals, which, unlike the major 
number of rodents, live on insects. The shrews, of which 
there are several species in this country, are small, mouse- 
like creatures, nocturnal in their habits, and hence rarely 
seen. The moles are of much larger size, and owing to 
their burrowing proclivities scarcely ever appear above 
ground, but excavate elaborate burrows with their shovel- 
like feet, devouring the insects which fall in their way. The 
common mole (Scalops aquaticus) extends from the eastern 
seaboard to the Mississippi River, where it is replaced by 
the prairie-mole (8. argenteus), which extends far to the 
west, into a country inhabited by other species. 
220. The bats (Cheiroptera).—The bats are also insectiv- 
orous, but their habits are widely different from those of 
the shrews and moles. The forearm and the fingers of the 
fore limbs are greatly elongated, and are connected by a 
thin papery membrane, which also includes the hind limbs 
and tail, and serves as an efficient organ of flight. During 
the day they remain suspended head downward in some 
dark cranny, awakening at nightfall to capture flying 
insects. Several species are found in this country, the 
most common being the little brown bat (Vespertilio fus- 
cus), with small, fox-like face, large erect ears, and short 
olive-brown hair. The red bat (Lasiurus borealis) is also 
plentiful everywhere throughout the United States, and is 
distinguished from the preceding by its somewhat larger 
size and long reddish-brown fur. 
221. The whales and porpoises (Cete)—The animals 
belonging to this order, the whales (Fig. 133), porpoises, and 
dolphins, are aquatic animals bearing a resemblance to fishes 
