TRACHEA. 



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simple : it consists of either one or two sub -globular bony chambers, 

 which have been called ampulla, a name we shall also retain. 



In most species of this division there is only one ampulla, and that 

 is situated on the left side ; but in the sheldrake, ( Tadorna Belonii, 

 Leach,) there are two ampulla, one on each side. Where there is 

 only one ampulla, the right bronchial tube is connected with the wind- 

 pipe, (trachea;) the left proceeds from the base of the ampulla. Where 

 there are two ampullce, the bronchia are partly connected with the 

 bony base of the windpipe, (trachea,) and partly with the ampulla, so 

 that there is a free circulation of respiring- air through those chambers. 



The structure here described will be better understood by the 

 figures annexed. 



A. Trachea of the white eye, Fuligula nyroca — a, the tympanum of the 

 labyrinth — b, the bony arch that crosses the tympanum — c, the 



bronchia. 



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