CLASS AVESI ORDER LAMELLIROSTRES. 153 



Fig. 258. 



1. Larus atricilla, Laughing Gull. 



2. Cygnus olor. Mute Swan. 



Fig. 259. 



ture a man's leg.* Swans fly high in their migration, to 

 keep "the sky" of rapacious birds. 

 They are said to live a hundred 

 years. 



The Canada Goose in the spring 

 migrates in great numbers to the 

 north to breed, and returns to the 

 tropics in the autumn. It always 

 flies in flocks, having the form of 

 an acute angle, the leader falling 

 back when fatigued, and the next 

 one taking its place. The sexes 

 are distinguished by the greater 

 length of the male's neck. They 

 are monogamous, but are supposed 

 to pair anew every spring. 



* This is explained by its swiftness, on the 

 mechanical principle that the effect increases 

 as the square of the velocity 



Bermcla canadensis, 

 Canada or Wild Goose. 



