514 
TRACHEA. 
TOPE. — A name for the Wren. 
TOR OUZEL. — A name for the Ring Blackbird. 
TRACHEA. — The trachea or aspira arteria, as the windpipe is 
scientifically called, is in some species of aquatic birds of a most singular 
structure, possessing an enlargement at the bottom, which has been 
termed a labyrinth. This labyrinthic part is of essential use to the or- 
nithologist, in discriminating the species, as well before their arrival at 
maturity, as in the several changes of plumage incidental to season. 
With a view to promote a discovery so essential, we propose to fix names 
to the several parts, in order to facilitate description. 
In the labyrinthic part of the windpipe, {trachea^ there is a material 
difference in conformation, which forms two natural divisions, and as 
might be expected, belong to birds of different habits ; one is a structure 
found amongst the diving-ducks with short wings, and some other 
birds, that collect their food mostly under water ; and as far as expe- 
rience has gone, this line of separation appears constant. There are, 
indeed, one or two species which deviate somewhat from either division, 
but do not connect the two. 
In order to explain this subject, we shall consider that the windpipe 
of such birds, consists of three principal parts ; that is to say, the wind- 
pipe, (trachea,') properly so called; the labyrinth, or swelling at the lower 
extremity ; and the divarications at the bottom, (hronchice,) which con- 
nect the windpipe, (trachea,) with the lungs. The principal distinc- 
tion in the labyrinth of the two divisions is as follows : — 
1. That which is composed of two distinct parts, one a compressed 
chamber, more or less covered with a thin membrane, situated on the 
left side of the windpipe, (trachea,) when in its proper place within the 
bird, which is called the drum (tympanum ;) at the back of which is 
another chamber, formed by the junction and inosculation of the base 
of the true divarications, (hronchice,) the cartilaginous or bony rings of 
which are more or less united by ossification ; a circumstance admirably 
exemplified in the labyrinth of the scaup-duck, (Fuligula marila, 
Stephens.) This part has been termed a bony box, (orca,) from its 
being usually x’ibbed like a dice-box, or the exterior and interior box, 
(orca.) From the bottom of the exterior box, (orca,) the flexible part 
of the right bronchial tube issues : the left bronchial tube arises from 
the base of the drum, (tympanum^ and is not in immediate contact 
with the interior box, (orca,) so that the respired air must first pass 
into the cavity of the drum, (tympanum^ in order to be received into 
the lungs. This is the labyrinth of the diving-ducks and mergansers. 
2. The labyrinth belonging to the grovelling-ducks is much more 
