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 fulfiUing all 

 these requirements. A series of l)ony rings is imbedded 

 in the wall of the trachea, beginning with that portion 



^^r^^^^^^^ -r 



Fig. 128. 



Fig. 129. 



Fig. 12S. — Windpipe of Flaminp;o, extended and contracted, showing delicate 



mechanism of siipportin^ rings. 

 Fig. 129. — Syrinx-dnim of Mullard Drake; the windpipe above; the bronchi 



below leading to the hings. 



inimedintely 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, ^^'hen 

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

 the windj)ipe of a flamingo, but the general structure 



