MUTE SWAN. 



211 



The whole length of an old male is from four feet eight 

 inches, to five feet ; the weight about thirty pounds ; and 

 marked Swans have been known to live fifty years. The 

 male is distinguished from the female by being larger ; the 

 black tubercle at the base of the beak is also larger ; the 

 neck is thicker, and the bird swims higher out of the 

 water. The body of the female is smaller ; the neck more 

 slender, and she appears to swim deeper in the water. 

 This latter point is referrible to a well known anatomical 

 law, that females have less capacious lungs than males, and 

 her body therefore is less buoyant. 



The young Mute Swan, in July, has plumage of a 

 dark bluish-grey, almost a sooty grey ; the neck, and the 

 under surface of the body rather lighter in colour ; the 

 beak lead colour ; the nostrils and the basal marginal line 

 black. The same birds, at the end of October, have the 

 beak of a light slate grey, tinged with green ; the irides 

 dark ; head, neck, and all the upper surface of the body, 

 nearly uniform sooty-greyish brown ; the under surface 

 also uniform, but of a lighter shade of greyish-brown. 

 Young birds at the end of October nearly as large as the 

 old birds. After the second autumn moult but little of the 

 grey plumage remains. When two years old they are 

 quite white, and breed in their third year. 



The figure here inserted represents the windpipe and 



