1 54 THE INDUSTRIES OF ANIMALS. 



Carefully-disposed burrows. — All the cases which we 

 have considered show us the industry of the hollowed 

 dwelling in its primitive state ; but other animals 

 know how to furnish it with greater luxury. I will 

 continue in the same order of increasing complica- 

 tion. Many beings live permanently in a burrow ; 

 Reptiles — Snakes or Lizards — are to be placed among 

 these. Among others, the Lacerta stirpium arranges 

 a narrow and deep hole, well hidden beneath a thicket, 

 and retires into it for the winter, when cold renders 

 it incapable of movement and at the mercy of its 

 enemies. Before giving itself up to its hybernal sleep, 

 it is careful to close hermetically the opening of the 

 dwelling with a little earth and dried leaves. When 

 spring returns and the heat awakens the reptile, it comes 

 out to warm itself and to hunt, but never abandons 

 its dwelling, always retiring into it in case of alarm 

 and to pass there cold days and nights. 



Darwin has observed and described' how a little 

 Lacertilian, the Conolophus subcristatns, conducts its 

 work of mining and digging. It establishes its burrow 

 in a soft tufa, and directs it almost horizontally, 

 hollowing it out in such a way that the axis of the 

 hole makes a very small angle with the soil. This 

 reptile does not foolishly expend its strength in this 

 troublesome labour. It only works with one side of 

 its body at a time, allowing the other side to rest. 

 For instance, the right anterior leg sets to work 

 digging, while the posterior leg on the same side 

 throws out the earth. When fatigued, the left legs 

 come into play, allowing the others to repose. 



Other animals, without building their cavern with 

 remarkable skill, show much sagacity in the choice of 



1 Voyage of the Beadle. 



