STRUCTURE OF BIRDS. 87 



has been seen in the skeleton figured in Plate I. The head is 

 composed of the brain, its membranes, the bones of the skull 

 and face, the organs of sight, hearing, smelling, and tasting, 

 with those of prehension and deglutition, and various other 

 parts. The neck is the more or less elongated and flexile part 

 by which the head is joined to the body, and is composed of 

 the cervical vertebras, various muscles, the oesophagus, the 

 windpipe, nerves, and blood-vessels. The body is the basis of 

 the whole, consisting of the dorsal and sacral vertebra, the ribs, 

 the sternum, the clavicles, the scapula, the heart, bronchi, 

 lungs, liver, stomach, intestines, kidneys, genital organs, and 

 various other parts. The tail is composed of the coccygeal 

 vertebrae, their muscles, and the quills. The anterior extre- 

 mity consists of the bones of the humerus, cubitus, and hand, 

 w^ith the muscles, and quills ; the posterior extremities of the 

 femur, leg, tarsus, and toes, with their muscles. All these 

 parts, excepting the bill, the nostrils, the eyes, the tarsi, and 

 the toes, are generally covered with feathers. 



Now, considering the Kestrel with reference to its exterior 

 only, we observe the following parts : 



The hill^ 1, 2, composed of two mandibles^ an upper, 1, and 

 a lower, 2, which are formed of horny substances ensheathing 

 the jaws. 



In the upper mandible are distinguished the base, 3 ; the 

 culmen or ridge, 4, of which the outline is named the dorsal 

 line ; the edges, 5 ; the point, 6. 



In the lower mandible are seen the base, 7, 8, distinguished 

 into the crura, 7, covering part of the rami of the jaw, and the 

 angle, 8, or junction of the crura ; the ridge, 9 ; the edges, 

 10 ; and the point. 



The cere, 11, which is not of general occurrence, is a portion 

 of bare skin at the base of the upper mandible. 



The nostrils, 12. 



The angle of the mouth, 13. 



The lore, 11, or part between the angle of the mouth and 

 the eye. 



The eye, 15, in which are distinguished the pupil or dark 

 central part, the iris or coloured circle surrounding the pupil, 



