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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, (bronchia,) 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, (bronchice,) 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 ribbed 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 



