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 
Fic. 128. Fic. 129. 
Fic. 128.—Windpipe of Flamingo, extended and contracted, showing delicate 
mechanism of supporting rings. 
Fic. 129.—Syrinx-drum of Mallard Drake; the windpipe ahove; 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 
