Feathers 



51 



closed they telescope so neatly beneath the fcatlieis of 

 the shoulder that they are not noticeable while the bird 

 is in either the autumnal or vernal plumage. 



As the feathers on the flipper-like wings of a penguin 

 resemble the scales of reptiles in ap})earance, so this 



Fig. 33a. — Ptarmigan in the fall, showing the gray autiiriinal plumage (wliich 

 has replaced the brown of summer on the upper parts of the body and wings), 

 gradually giving place to the white of the coming winter feathers. Wild 

 birds in Alaska. (Harold Whealton, photographer.) 



homology is carried out in the method of shedding them. 

 Unlike the dropping out of feathers one by one, as in 

 other birds, these come off in flakes, like the skin of a 

 lizard. The feathers of the back loosen, shrivel up, and 

 fade to a brownish hue before they peel away. 



