56 THE WANDERINGS OF ANIMALS [OH. 



It would be absurd to conclude that cold is a more 

 favourable factor to life than warmth. It is quite 

 a different question whether a change from hot to 

 cold may not have a profoundly stirring influence upon 

 organisms. The Permian period was one of widely 

 spread coolness, which has played havoc at least 

 with the marine fauna, by reducing its numbers of 

 individuals and species, but it also ushered in, or 

 prepared, a new and remarkable terrestrial verte- 

 brate fauna. Our last northern glacial epoch may 

 have killed out much of the warm Pliocene life, but it 

 has given us the present arctic fauna, which is very 

 considerable, and remarkable for being very up-to- 

 date, singularly free from old-fashioned types. The 

 place for these are the tropics, because there the 

 climate has changed least in the equatorial belt, 

 which seems to have been hot since the Triassic 

 period. 



A statement which has been repeated so often 

 as to amount almost to a creed, is that the typical 

 animals and plants of snow mountains in the temper- 

 ate and even in the tropical regions have their nearest 

 relations in the arctic regions ; that they are derelicts, 

 shut off* by the recession of the glacial epoch, instead 

 of being modifications, suited to a more rigorous 

 climate, of the lower or basal faunas of the country 

 in which these mountains are situated. This is a 

 much overrated statement. These faunas and floras 



