TRACHEA. 515 
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 ampullce, one on each side. Where there is 
only one ampulla, the rig-ht 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 ampullce, 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 
bronchice. 
L L 2 
