394 THE LIFE OF A BIRD. 



support, or in prehension, or seizing hold of any 

 object." 



Birds are therefore biped, and the operations of 

 taking the food, cleaning the plumage, &c., are 

 almost exclusively performed by means of the 

 mouth, which consists of two mandibles without 

 teeth or lips, sheathed with horn, in order to ren- 

 der more easy the seizing and other actions thus 

 transferred to the head ; the neck is elongated, 

 and the body is generally inclined forwards and 

 downwards from the hip-joints; the thighs are 

 accordingly extended forwards at an acute angle, 

 towards the centre of the trunk, and the toes are 

 lengthened and spread out so as to form an ade- 

 quate base of support. The various actions of 

 perching, walking, running, scratching, burrowing, 

 wading, and swimming, require for their perfect 

 performance different modifications of the legs. 

 The mandibles, or beak of the bird, present as 

 many varieties of form, each corresponding to the 

 nature of the food, and in some degree indicating the 

 organization necessary for its due appropriation to 

 the wants of the bird. In consequence of these vari- 

 ations in the feet and bill, ornithologists have founded 

 their divisions of birds chiefly upon the modifica- 

 tions of these organs presented by different birds. 



