168 The Bird 



and elastic, in order to stretch and contract as the bird 

 reaches out or draws back its head. 



We find a most ingenious arrangement fulfilling all 

 these requirements. A series of bony rings is imbedded 

 in the wall of the trachea, beginning with that portion 



FIG. 128. FIG. 129. 



FIG. 128. Windpipe of Flamingo, extended and contracted, showing delicate 



mechanism of supporting rings. 

 FIG. 129. Syrinx-drum of Mallard Drake; the windpipe above; the bronchi 



below leading to the lungs. 



immediately back of the glottis, and extending through- 

 out its entire length. The membrane which connects these 

 rings is so elastic that a section of trachea can be drawn 

 out until it is twice as long as when contracted. When 

 in the latter condition (I have in my hand an inch of 

 the windpipe of a flamingo, but the general structure 



