X. 
HABITS AND FACULTIES. 
The animals of this order, indigenous to the United 
States, are essentially inhabitants of the forest. It is 
there, under the deep shadows of a dense foliage, where 
the sun's rays hardly penetrate to the surface of the 
earth, and where the ground is covered with the mould- 
ering trunks of trees and thick layers of decaying 
leaves, that they find a constant moisture, a twilight 
interrupted only by darkness, abundance of vegetable 
and animal food, and the means of shelter and protec- 
tion. These constitute a combination of circumstances 
very favorable to then- increase, and hence they may be 
discovered, in situations where these conditions exist, in 
every part of the country where they can be found at 
all. But when, with these, are conjoined a mild climate, 
and a calcareous soil, the maximum of favoring influences 
is reached, and large numbers are produced. It is in 
the great valley of the Mississippi, based throughout 
nearly its whole extent upon horizontal limestone forma- 
