48 THE BONES. 



we shall call the heel bone, at c, is fitted in a very 

 curious manner into the lower part of the leg bone 

 above it, and precisely answers the purpose required 

 of the bird, affording a sufficient degree of resistance 

 by the bending of the leg, to counteract the effect 

 of any overbalancing of the body. The bird, more- 

 over, has a power over this well-contrived prop, and 

 thus bends its leg or keeps it perfectly stiff, as best 

 suits its convenience. 



