Mr. YARRELL on the Trachee of Birds. 379 
The Crested Pintado of Africa, the Numida cristata of Pallas, 
described and figured in Dr. Latham's General Synopsis, vol. iv. 
p. 638, and in his General History, vol. viii. p. 148, exhibits 
an extraordinary structure, to which I shall first advert. "That 
part of the'os furcula, or merrythought as it is more commonly 
called, which in our common Guinea Fowl consists of a single flat 
blade descending from the apex or junction of the two branches, 
is in this bird double, one side appearing to extend from each 
‘branch ; it is also somewhat circular, and united at the edges 
throughout the greater part of the circumference, forming a 
socket or pouch. "The trachea, quitting the neck of the bird at 
the lower curve of the cervical vertebræ, passes downward be- 
tween the branches of the furcula, enters the pouch at the lower 
part of the orifice, traverses the inner surface, and issuing from 
the upper part, rises with a circular sweep, upward and forward 
to the projecting anterior portion of the sternum, over which it 
turns backward to pass into the body ; guided in its course by 
two semi-transparent membranes, stretching from this projection 
of the sternum to the head of each clavicle. 
If a line be drawn from the commencement of the trachea, as 
shown in the figure, to the bronchia, passing between the sca- 
pulz, it will describe the situation of the trachea in our common 
domestic Guinea Fowl, and the variation of the crested bird will 
appear the more extraordinary by comparison. 
For the opportunity of figuring this singular structure, I am 
indebted to the liberality of the Board of Curators of the Royal 
College of Surgeons, and to the friendship of Mr. W. Clift, jun., 
for a beautiful drawing from a specimen in the Museum of the 
College, the only one I ever had an opportunity of examining. 
From that drawing the one now annexed is a close copy. 
M. Temminck has described this bird in his Histoire Natu- 
relle Générale: des Pigeons et des Gallinacés, vol. ii. p. 448, 
under 
