DOMESTIC LIFE. 145 



Thus the Common British Grass-Snake (Tropi- 

 donotus natrix) and the Viper (Fipera lerus) on 

 the approach of winter seeks out some sheltered 

 hole in a bank, or under the roots of trees, and 

 in a state of torpor await the spring. Though 

 commonly they retire singly, they are not un- 

 frequently found huddled together in masses 

 of considerable numbers. With the Common 

 Rattle-snake (Crotalus horridus) of North America, 

 this custom of hybernation in large masses is 

 apparently the rule rather than the exception. 

 Assembling, it is said, in thousands from a radius 

 of twenty or thirty miles they meet, in the 

 ancestral den, to pass the winter in a state of 

 torpor, huddled together for the sake of warmth. 

 This "homing" instinct is, of course, of the 

 same nature as that which guides the swallow 

 back to its old nest, or the salmon back to the 

 same river, for nesting purposes. 



Among the Crocodilia extremes of climate are 

 avoided in one of three ways hybernation, 

 aestivation, and migration. Thus the Alligator 

 (A. missisippiensis) passes the cold season in a 

 state of torpor in holes in the ground; whilst 

 the Marsh Crocodile (C. palustris) of, India and 

 Ceylon passes periods of drought buried in the 

 mud, remaining there, in a torpid condition, till 

 the rains. The large Caiman (Caiman jacar) of 

 South America, apparently disapproving of this 

 waste of time, avoids unpleasant extremes by 

 migrating, retreating to the flooded forests in 

 the wet season, and returning to the rivers in 

 the dry season. 



The Lizards and Tortoise-tribe also hybernate 

 K 



