THE ARCTIC LANDS. 



23 



tinuous belt, stretching through three parts of the world, in a breadth of from 

 15 to 20, even the woods of the Amazon, which cover a surface fifteen times 

 greater than that of the United Kingdom, shrink into comparative insignifi- 

 cance. Unlike the tropical forests, which are characterized by an immense 

 variety of trees, these northern woods are almost entirely composed of conif-' 

 era?, and one single kind of fir or pine often covers an immense extent of 



