300 FIELD ZOOLOGY. 



ear coverts instead. The drum of the ear is very near the 

 surface of the head. In the middle ear, the complex 

 mechanism found in the human ear is reduced to a single 

 bone, the columella ; and the tympanic cavity is connected 

 with the mouth by a broad passageway, instead of the 

 slender Eustachian tube of the human ear. In the inner 

 ear, the cochlea is shorter and is not coiled tightly; 

 neither do the semicircular canals have the position of 

 these organs in the human ear. They lie in three separate 

 planes in the ear of the bird. 



Taste. 



The principal organ of taste is the tongue, which is 

 innervated by the glossopharyngeal nerve, whose branches 

 go to the back part of the mouth as well as to the tongue. 

 The sense is intimately connected with the sense of smell. 



Touch. 



The beak is the principal organ of touch, although 

 there is a distributed sense of touch, not localized but 

 distributed over the entire body, and having definite 

 connection with the down or feather covering. 



Respiration. 



The lungs of birds are not, as in mammals, hemmed 

 into a thoracic portion of the chest or thorax, but are 

 more like the lungs of reptiles. They begin at the apex 

 of the chest in front and extend backward in the upper 

 region of the thorax and the vertebrae as far as the kid- 

 neys. They are not lobed nor do they float free, but are 

 fixed in the upper portion of the dorsal cavity, and are 

 covered on the lower side with a membrane or pleura. 

 The air enters the nostrils, but does not, as in the human 

 animal, pass through the windpipe directly to the lungs. 



