LOCOMOTION. 



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walk as we may say on tiptoe. As they have their 

 centre of gravity, however, not directly over their 

 legs, but more forward, it requires peculiar contriv- 

 ances in their formation to enable them to balance 

 themselves on their toes. Accordingly birds have 

 their toes for the most part proportionally much 

 longer than other animals, while the great flexion of 

 the leg upon the thigh brings the toes more under the 

 centre of gravity. 



Feet of Water Birds in the act of making the back-stroke in swimming. 

 a, The Diver. b\ The Cormorant. c, The Gribe. d, The Phalarope. 



Birds have this further peculiarity, that the standing 

 posture is their state of most perfect rest, arising 

 from the structure of their legs, as first explained by 

 the old Italian naturalist, Borelli. The tendons of the 

 muscles which bend the claws pass over the joints 

 of the heel, and are joined there by another muscle 



