1886. ] ANATOMY OF CHAUNA CHAVARIA. 179 
former group, since the lobes of the liver are not shut off by septa 
from the space which lies between the horizontal membrane and the 
ventral abdominal walls. In the Cranes, as in the Struthious birds, 
the lobes of the liver are enclosed in separate compartments distinct 
from that underlying the horizontal membrane (cf. P. Z.S. 1885, 
p. 836). 
There are other points in which Chauna approaches the Storks, 
In the paper already referred tc, Weldon has drawn attention to a 
peculiarity in the air-sacs of the Storks which appears to be 
characteristic of this group, and is at any rate not to be found in 
the Ducks. The prebronchial air-sacs (in the Storks and Pheeni- 
copterus) are divided by a complicated arrangement of transverse 
septa into smaller chambers. 
In Chauna chavaria this subdivision of the preebronchial air-sacs 
is very much more marked, and the subbronchial air-sacs, which in the 
Storks and many other birds are fused into a single cavity, are in the 
same way divided up into an immense number of extremely small 
chambers, so that the whole air-sac presents the appearance of a 
crowd of air-bubbles closely pressed together of various sizes. It 
was quite impossible on this account to distinguish the prebronchial 
from the postbranchial sacs, that is to say at the points where they 
come into contact. 
The prolongations of the subbronchial air-sacs into the axilla and 
into the space between the two pectoral muscles were similarly sub- 
divided by innumerable septa. 
There appeared to be nothing remarkable in the disposition of the 
abdominal air-sacs, and there were no indications of any subdivision 
of these charmbers; the anterior intermediate air-sac cominunicates 
with the bronchus by two apertures placed side by side and at some 
distance from each other near the anterior end of the. chamber; 
in the posterior intermediate sac, which was considerably the larger 
of the two, there was only a single pulmonary orifice. 
The abdominal air-sacs present the usual character—the right 
being considerably larger than the left. 
It appears to be the general rule that the thoracico-abdominal air- 
sacs are not divided up in the way that the cervical air-sacs are in 
Chauna and in the Storks; but I have met with occasional variations 
in the structure of their air-sacs in some few out of the numerous 
birds which I have had the opportunity of dissecting. In Steatornis 
I have already (supra, p. 151) called attention to the fact that 
the posterior intermediate air-sac was either completely separated 
into two distinct compartments or had indications of such a division ; 
in a specimen of Striv flammea there was a similar division of the 
posterior air-sac, at least on one side of the body. The third instance 
is Platalea leucorodia ; in a specimen of this bird, on both sides of the 
body there were three ‘intermediate ”’ air-sacs, the third being very 
small and interpolated between the anterior and posterior intermediate 
sacs. This may of course be an abnormality’; but the air-sacs of 
birds differ so little that any fact seems worth recording ; and the 
* A second specimen had the normal number of abdominal air-sacs. 
