ON THE LEGS AND FRET OF BIKDS. 349 



Muscles which bend the leg: and foot of birds, a, b, the muscle arising from the head of the 

 thigh bone ; c, d, the knee over which it runs ; e, its passage over the heel, and along the 

 shank ; /, to the toes, g,g,g, g. 



In consequence of this curious mechanism, a bird is more perfectly 

 at rest when standing than in any other position ; for by letting the 

 weight of the body fall on the thigh, this is not only bent itself, but 

 without effort bends the toes inward, so as to grasp the bough of a tree, 

 or whatever the bird stands upon. As the toes will also grasp more 

 strongly in proportion to the weight thrown upon them, it follows, that 

 by throwing the whole weight of the body upon one leg, rather than on 

 both, the bird will be fixed more securely ; and hence it is that birds 

 most generally rest, or sleep, standing on one foot, with their head 

 turned back, behind the wing, to throw the greatest possible weight 

 directly over the leg. 



The objections made by Vicq-d' Azyr and Barthez to this ingenious 

 explanation, first given by Borelli, have been refuted by Dr. Barclay. 



Most of the smaller birds, such as sparrows and magpies, hop or 

 skip, but some walk by moving the legs alternately, as the larks, wag- 

 tails, and the blue breast. The bullfinch and the tits walk sideways, 

 up and down branches. Rooks and jackdaws swagger in their walk, 

 and the stork throws out its feet in a stalking manner, while all poultry 

 walk with a parading and not ungraceful strut, very different indeed 

 from the awkward roll of the goose, or the waddle of the duck. In 

 water birds, the bone of the shank is thin, and the skin sharp, while on 

 bringing forward the foot, the toes close behind each other, so as 

 to present but a small surface, and hence, in swimming, little velocity 



VOL. i. NO. viii. (AUGUST, 1833.) B B 



