CHAPTER XV. 



THE NEARCTIC EEGION. 



This region consists almost wholly of Temperate North America 

 as defined by physical geographers. In area it is about equal 

 to the Neotropical region. It possesses a vast mountain range 

 traversing its entire length from north to south, comparable 

 with, and in fact a continuation of^ the Andes, — and a smaller 

 range near the east coast, equally comparable with the mountains 

 of Brazil and Guiana. These mountains supply its great river- 

 system of the Mississippi, second only to that of the Amazon ; 

 and in its vast group of fresh-water lakes or inland seas, it 

 possesses a feature unmatched by any other region, except 

 perhaps by the Ethiopian. It possesses every variety of climate 

 between arctic and tropical ; extensive forests and vast prairies ; 

 a greatly varied surface and a rich and beautiful flora. But these 

 great advantages are somewhat neutralized by other physical 

 features. It extends far towards the north, and there it reaches 

 its greatest width ; while in its southern and warmest portion it 

 suddenly narrows. The northern mass of land causes its 

 isothermal lines to bend southwards ; and its winter tempera- 

 ture especially, is far lower than at corresponding latitudes 

 in Europe. This diminishes the available area for supporting 

 animal life ; the amount and character of which must be, to a 

 great extent, determined by the nature of the least favourable 

 part of the year. Again, owing to the position of its mountain 

 ranges and the direction of prevalent winds, a large extent of its 

 interior, east of the Eocky Mountains, is bare and arid, and often 

 almost desert ; while the most favoured districts, — those east of 



