502 Mr. BnRooxzs on the Formation of the Trachea 
nary structure of the trachea: quans, curassows, the caperkally, 
and Phonygama Keraudrenii, are instances of those exceptions. 
Nothing striking in this respect occurs in individuals of the 
order Raptores, all of which have an ingluvies, with an os furci- 
forme very strong, and bent concavely for its support; whereas 
in the Rasores the same bone is of so delicate a nature, that in 
one of the largest species, the turkey, it is even of a slighter 
texture, in proportion to the size of the bird, than in all the 
other genera. This circumstance arises probably from the spe- 
cies of this order being constructed more for walking than 
flying; the turkey especially, whose migrations are sometimes 
of considerable extent, performing them chiefly on foot. The 
Struthionide have no perfect os furciforme. 
I hope to be understood as not implying that there is no 
peculiarity of the larynges and tracheæ, except in some genera; 
for I believe all have the admirable mechanism of the organ of 
voice differently constructed, with corresponding muscles, and 
distribution of nerves, producing those various modulations of 
sound so familiar to us, and destined for the excitement of love, 
as well as for other purposes. 
It would seem superfluous in me to offer further observations 
on this head, after the luminous representations which are to be 
found in different authors, demonstrating these facts, but more 
particularly by Mr.Yarrell, who favoured the Society with highly 
interesting details of this curious subject, illustrated by prepa- 
rations, and drawings of the remarkable forms of the labyrinths, 
larynges, divaricating septa, and extensive contórtions of the 
trachez in various species, as well as of the appropriate muscles, 
some of which were before altogether undescribed. 
It may be thought worthy of remark, that the Tantalus affords 
the only instance, I am acquainted with, except the spoonbill, 
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