CHAPTER XV. 
THE NEARCTIC REGION. 
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 Rocky Mountains, is bare and arid, and often 
almost desert ; while the most favoured districts, — those east of 
