THE EBSPIEATOEY STSTHM, 2 1 1 



of the uppermost part o£ our own trachea, which is called the 

 larynx. In us this is the organ of voice, but it is not so in 

 Birds. 



The windpipe of Birds is kept in the form of an open tube 

 by a numerous series of generally complete bony rings in its 

 substance. It is very long and often convoluted, sometimes 

 making a coil within the sternum, and sometimes possessing 

 subcutaneous dilatations, as in the Emeu, where some of the 



Fig. 162. 



Sykinx of Eaven. 

 Lowest part of trachea and roots of the two bronchi. 



a, Front half-ring of bronchus ; b, second (more moveable than the first) ; 

 0, third half-ring — connected with the second by ligament and 

 membrane. 



rings are incomplete in front. In the Penguin the trachea has 

 a longitudinal septum. At its lower end the trachea bifurcates 

 and its two branches, which lead into the lungs, are called 

 hronchi. 



The organ of voice in Birds is called the syrinx or lower larynic, 

 because it is placed much lower down than our own organ of 

 voice. Indeed, such a structure as the " syrinx " is absolutely 

 peculiar to the Class of Birds. Its general condition is as 

 follows. It is formed by the coalescence and modification in 

 shape of the lower rings of the trachea and the upper rings of the 

 bronchi, the latter being incomplete internally, so that the sides 



P 2 



