i SSs . J Kitchen on the Inferior Larynx in Birds. 2 7 



expiration of air is effected by a decided muscular effort, drawing 

 the largely developed breast-bone towards the spine, and this 

 forces the air out of the body, while inspiration, or the drawing 

 of air into the body, is the result of the resilient recoil of the 

 breast-bone, and the rest of the tissues making up the chest walls. 

 This action is just opposite to the respiratory method in man, 

 where ordinary inspiration is effected by decided action on the part 

 of the respiratory muscles, especially of the chief respiratory 

 muscle, # the diaphragm. This physiological peculiarity in birds 

 gives them the ability to emit such powerfully loud and long- 

 continued notes with little apparent effort. This is particularly 

 to be noticed in small birds, such as the Canary and Black-poll 

 Warbler. (2) The resounding cavities and articulating structures 

 are very different from those in man. The trachea is a very 

 much more distensible tube. Its rings are bony and complete. 

 It is formed so as to be retracted or distended to a remarkable 

 degree, through the action of the peculiar external tracheal mus- 

 cles. This construction enables the organ to produce the effects 

 of pitch or range in the notes of the musical scale, and also makes a 

 good resounding medium, being in this respect analogous to an 

 organ pipe. In the throat and mouth we find no soft palate, or 

 pharyngeal vault, and hardly a trace of an epiglottis. Birds are 

 very deficient in their powers of articulation, owing to the pecul- 

 iarities of construction in the throat and mouth. The fleshy 

 tongue of the Parrot gives that bird exceptional powers in this 

 respect; but even the stiff, horny, and comparatively immobile 

 tongue of other birds is capable, by its action, of producing the 

 'twittering,' 'whistling,' and other effects. The muscular floor- 

 ing of the mouth, by its ability of contracting in a rapid flutter- 

 ing manner, is very evidently capable of producing the 'warbling' 

 effect. (3) The third and most marked deviation in birds from the 

 vocal mechanism of man, is in the phonating or tone-producing 

 structure. Instead of having one concentrated 'vocal box,' located 

 at the top of the trachea, and which in itself contains all the parts 

 necessary for regulating the pitch and some other qualities of the 

 tone produced, birds have two larynges : the superior larynx 

 being located as in man at the top of the trachea, while the 

 inferior larynx or syrinx, is located at the inferior extremity of 

 the trachea, at its point of bifurcation into the right and left bron- 

 chial tubes. This complex construction, that may be used for 



