i68 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 fulfilhng 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 



mechani.sni of svipporting rings. 

 Fig. 129. — Syrinx-drum of Mallard Drake; the windpipe al-ove; the bronchi 



below leading to the lung.s. 



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 w-hen contracted. When 

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

 the windpipe of a flamingo, but the general structure 



