1 00 THE ANATOMY OF BIRD-SONG. 



II. 



In his description of the syrinx, Huxley, 

 taking it for granted that bird-song is gener- 

 ated in that organ, declares: "The voice of 

 birds is not formed in the larynx, but in the 

 eyrinx." 



To understand what is meant by this state- 

 ment, let us examine the anatomy of a typical 

 bird-syrinx. If for this purpose we kill a 

 rook, as did Macgillivray, and proceed to cut 

 out its tongue with the entire tracheal column 

 attached, we shall find that the opening of 

 the trachea is just posterior to the root of the 

 tongue. From this opening, down to where 

 it is divided into two bronchial tubes, the 

 trachea of most song-birds slightly decreases 

 in diameter. At the point of division, how- 

 ever, a peculiar modification of structure 

 takes place. This modification of the trachea 

 is the syrinx, which, viewed exteriorly, is a 

 roundish bundle of muscular fiber covering 

 the bony and cartilaginous frame of the 

 organ, whilst its interior is a delicate but 

 firmly adjusted system of valves. The main 

 body of the tracheal column is an elastic tube 

 of long rings held together by a tough and 

 flexible covering, and furnished with muscles 

 by which it may be shortened or elongated at 

 the will of the bird. 



The glottis, as the opening of the trachea is 

 called, is a slit somewhat elliptical in its 

 general form, set between the barb-like 

 prongs of the hyoid bone. This opening is 

 furnished with a rim of muscle and mem- 

 brane and can be opened, closed, or made to 

 assume a great variety of forms at the bird's 

 will. Immediately over the glottis, in the 

 roof of the bird's mouth is a narrow longi- 

 tudinal groove that in its anterior extremity 

 ips exactly formed to receive the bony tip of 



