INSECT-EATING MAMMALS 65 



is being formed) is permeated above the globular inner cavity by 

 a series of galleries, some of which are blind alleys, while others 

 open out into the air, generally below the outer surface of the 

 molehill, but sometimes at points in the sides of the dome itself. 

 The main entrance, the high road, so to speak, into the fortress 

 has a circumference larger than the body of the mole, though not 

 large enough to permit of two moles passing each other. Indeed, 

 should an intruder meet the owner of the domain, the two moles 

 must either fight for mastery, or one of them must back into 



Molehill 



PLAN OF THE INTERIOR OF AN ORDINARY MOLEHILL. 



a side alley and give way. This long tunnel as widened and 

 heightened more by the constant passage of the mole's body than 

 by excavation. The mole, so to speak, forces his way through 

 the yielding soil, and by the compression of the earth makes the 

 sides of the passage smooth and compact. This high road 

 extends right through the mole's domain, and opens to the 

 surface at a considerable distance from the fortress. It is paralleled 

 on the other side of the nest by another passage, much shorter, 

 however, generally called the "bolt run," which is, in fact, 

 a short exit from the fortress to the upper surface of the 



