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the left proceeds from the base of the am- 
pulla, but, in those species with two am- 
pulla?, the bronchia are partly connected 
with the bony base of the trachea, and 
partly with the ampulla, so that there is 
a free circulation of air through those 
chambers. 
This will be better understood by a re- 
refence to the trachea of Anas hoschas, 
(Mallard) Plate IV. 
WITH ONE AMPULLA BUT NO TYMPANUM. 
Fig. 3. a, the front of the ampulla, b, 
the bronchia, 
WITH TWO AMPULLiE BUT NO TYMPANUM. 
Refer to the trachea of Anas tadorna, 
(Shiddrake)^ 
* Altho' the genus Mergus does not slrictly belong 
to this place, we, have thought proper, in order that an 
easier reference may be made, to introduce plates of the 
trachece belonging to the British species of that genus; 
see Plates I. and II. 
