THE ANIMAL KINGDOM. 



329 



the polar circle to the tropical regions; the cranes pass 

 the summer on the stormy strands of Scandinavia and 

 the winter amid the ruins of the palaces of the Pharaohs. 



185. Crane's Nest on an Egyi^tian Monument. 



The mechanism of birds is admirably suited to aid their 

 rapid flight. Their aerial oars, moved Ijy muscles of extra- 

 ordinary power, easily adapt themselves to all the hazards 

 of their peregrinations through the elevated regions of air. 



