WINGS AND FEET 



used for propulsion under water. The penguins, 

 although entirely distinct from the auks, fly 

 through the water with their extended flipper- 

 like wings, and, from the testimony of those 

 who have watched them in tanks, it is learned 

 that the feet are not used. Thus Lea * says of 

 these curious birds: "Their flight may be 

 watched and studied in the large glass tanks 

 at the Zoo. . . . With short, rapid strokes of 

 its paddle wings it darts through the water 

 leaving a trail of glistening bubbles behind, 

 and shoots forward with the speed of a fish, turn- 

 ing more rapidly than almost any bird of the 

 air by the strokes of the wing alone, the legs 

 floating apparently inert in a line with the 

 gleaming body, or giving an occasional upward 

 kick to force it to greater depths." 



One is apt to assume that " the trail of 

 glistening bubbles " which comes from a diving 

 bird are the expired air bubbles, but I am 

 inclined to think that most if not all of this 

 air is expelled from the feathers in order to 

 make diving more easy or even possible. Some 

 diving birds have the ability to sink gradually 

 out of sight in the water with apparently little 



1 John Lea, The Romance of Bird Life, 1909, pp. 202-203. 

 191 



