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termed a bony box or orca, from its be- 
ing usually ribbed like a dice box. From 
the bottom of the exterior orca, issues the 
right bronchial tube; the left from the 
base of the tympanum, which is not in 
immediate contact with the interior orca, 
so that the respired air must first pass into 
the cavity of the tympanum, in order to 
be received into the lungs. 
We will examplify the above, by a re- 
ference to the trachea of Anas clangula, 
(Golden Eye) Fig. I, Plate III, a, the 
tympanum of the labyrinth. — b, the bony 
arch that covers the tympanum. — c, the 
bronchice. 
Fig. II, — labyrinth of ditto reversed. — 
a, the back of the tympanum. — b, the ex- 
terior orca. — c, the interior orca. 
The labyrinth belonging to the second 
division, is much more simple : it consists 
of either one, or two sub-globular bony 
chambers, which are called ampullae. In 
most of the species belonging to this divi- 
sion there is only one ampulla and that is 
situated on the left side, the right bron- 
chial tube is connected with the trachea ; 
