18 
gives off the bronchial and intercostal arteries above the diaphragm. The latter are 
three or four in number, which divide and form the usual plexiform anastomoses round 
the heads of the ribs, with branches of the vertebral arteries ; from which plexuses the 
proper intercostal branches are continued. The celiac avis, having perforated the dia- 
phragm, divides and supplies the stomach, liver, and spleen in the usual manner. The 
mesenteric artery offers nothing unusual in its mode of distribution. The deaphragm 
is itself supplied by branches from the intercostal plewuses, and there are no proper 
phrenic arteries. 
The first branch which the aorta sends off, after having entered the abdomen, is the 
spermatic artery (PI. VI. 0, fig. 1.); this was of moderate size in the large male 
Apterye, and soon divided into two branches, which were distributed respectively to 
the corresponding testis and supra-renal gland. 
The aorta having reached the first lumbar or sacral vertebra, sends off the femoral 
arteries (p, p, fig. 1.), which are of equal size with the ischiadic arteries afterwards given 
off. The femoral is continued outwards on each side at right angles with the aorta, 
sends a small branch to the upper lobe of the kidney and passes out of the pelvis, not 
through a notch or foramen, as in most other birds, but simply over the margin of the 
iliac bone. It is continued upon the thigh, covered by the wide and strong sartorius, 
where it divides into two principal branches, of which one is distributed to the sartorius, 
gracilis, vasti, and other muscles at the anterior and upper part of the thigh; and the 
second branch is continued to the knee-joint, where it ends by forming anastomoses 
with the ischiadic. ‘The aorta next sends off a pair of renal arteries (q, q, fig. 1.) of 
moderate size, beyond which it may be said to resolve itself into the ischiadic (r, r,) 
and sacro-median arteries (s, fig. 1.). The ischiadic branches are not here, as in most 
other birds, the main arteries of the hinder extremities ; they do not exceed the femo- 
rals in size, and are principally expended upon the muscles of the leg: they escape 
from the pelvis as usual by the ischiadic foramina, and are continued down the back 
part of the thigh external to the adductor magnus, covered at first by the broad biceps 
cruris, and afterwards continued between the biceps and the vastus eaxternus to the 
outer side of the popliteal space: here the artery accompanies the ischiadic nerve and 
the strong tendon of the biceps between the two heads of the gastrocnemius externus, 
and through the tendinous trochlear loop connected with that muscle, where it divides, 
and is finally distributed as in other birds. 
The sacro-median artery, after sending off a small branch to the rectum, divides into 
the genital or hypogastric and the coccygeal arteries. 
I did not observe any modification of that condition of the venous system which 
usually characterizes the class of birds. 
The inferior cava does not perforate the diaphragm, but enters the posterior part of 
the pericardium just above the anterior fissure of the diaphragm: it receives, close to 
its termination, the two large hepatic veins. ‘There exists the same disposition of the 


