748 MR. FLOWER ON THE GULAR POUCH OF THE BUSTARD. [ Dec. 12, 
the parts, the opening is reduced to a T-shaped slit (the crosspiece, 
two lines long, being turned backwards), surrounded by well-marked 
deep folds of mucous membrane, which coming into apposition with 
each other close the orifice. These folds have a perfectly definite 
arrangement : traced up from the mouth of the orifice, the posterior 
ones are lost on the under surface of the tongue ; those coming from 
the two sides diverge from each other, and run round the lateral 
parts of the base of the tongue; those from the anterior wall of the 
opening are continuous with the longitudinal folds on the middle of 
the floor of the mouth. The arrangement of these folds admits of 
great dilatation of the aperture, so that it will quite readily admit the 
introduction of the finger. When slightly distended, the opening 
becomes triangular, the hinder border straight and placed transversely 
at the base of the tongue; the apex, turned forwards, is continuous 
with the groove in the middle line of the floor of the mouth. 
The pouch to which this opening leads is suspended by a some- 
what constricted neck to the floor of the mouth, between the hinder 
part of the rami of the mandible; it may indeed be looked upon as 
a dilatation of that part of the floor situated immediately in front of 
the base of the tongue. A distinct but not very strong band of 
muscular fibres runs immediately beneath the mucous membrane of 
the mouth, on each side of the neck of the sack, meeting before and 
behind—evidently the sphincter mentioned by Dr. Cullen. It ap- 
pears, however, to be only a part of the general muscular layer ex- 
tending between the mandibles and the hyoid bone. 
The sack itself when empty measured 9 inches in length, and, 
when moderately distended by allowing water to run in by its own 
weight, without any forcing, was found to hold three imperial pints ; 
probably it could have been easily made to contain more, but that I 
did not wish to run any risk of bursting it. When thus distended 
it had an elongated pyriform shape, the larger end being turned 
upwards. Rather below the middle there was a gentle constriction. 
The walls of the sack are formed of a thin but perfectly distinct and 
tolerably strong membrane, composed of intersecting bundles of pale 
unstriped muscular fibres, united by connective or areolar tissue, and 
having numerous blood-vessels ramifying upon it. Externally it has 
evidently been but slightly connected with the surrounding parts by 
a loose areolar tissue. Internally it is smooth and lined by a dis- 
tinct epithelium, continuous above with that of the mucous mem- 
brane of the mouth. 
Both of the sacks had within them a few short pieces of grass 
and leaves*. There appears to be no glandular structure connected 
with the walls; indeed the whole character of the sack points to its 
being a simple reservoir, probably for fluid, more analogous to the 
submandibular pouch of the Pelican than to anything else in the class 
Aves. But in the absence of fuller information as to the economy 
and habits of the bird, I refrain from speculating upon the purpose 
of this singular and apparently inconstant organ. 
* Grass-seeds have been observed by Naumann in the pouch of a Bustard 
(Newton, Joc. cit.). 
