670 BIRDS. 
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(a) The arterial trunk, as it rises from the heart, gives off on each 
side an innominate artery. Each innominate gives off a carotid 
and a subclavian, and the subclavian immediately divides into 
a brachial to the arm and a pectoral to the breast muscles. 
(6) The dorsal aorta, formed by a continuation of the arterial trunk 
bending round on the right side, gives off coeliac, mesenteric, 
renal, femoral, sciatic, iliac, and other arteries. 
(c) The pulmonary arteries carry impure blood from right ventricle 
to lungs. 
The venous system consists of the following vessels (Fig. 371) :— 
(a) Two superior venze cavee, each formed from the union of 
jugulars from the head, a brachial from the arm, and a pectoral 
from the breast. 
(4) The inferior vena cava is formed from the junction of two iliac 
veins just in front of the kidneys. Each of these iliacs results 
from the union of a femoral from the leg, an efferent renal 
from the kidney, and a ‘‘renal-portal,” or hypogastric, which 
passes upwards through the kidney. To understand this hypo- 
gastric, it is convenient to begin at the tail. A short caudal 
vein divides anteriorly into right and left branches, each of 
which receives an internal iliac from the sides of the pelvic 
region. Thus the hypogastric is formed at each side, and 
this, passing upwards through the kidney, receives the sciatic, 
and finally joins with the femoral and with the renal. 
(c) The pulmonary veins carry pure blood from lungs to left auricle. 
The hepatic portal system is as usual,—mesenteric veins from the 
intestine combine in portal veins; the blood filters through the liver, 
and is collected in hepatic veins, which unite with the anterior end of 
the inferior vena cava. 
A hint of a renal-portal system is represented by small branches, which 
the femorals give off to the kidney. 
From the transverse vein formed between the two hypogastrics or by 
the division of the caudal vein, a coccygeo-mesenteric arises, which 
receives vessels from the cloaca and large intestine, and is continued 
along the mesentery to join the hepatic portal system. 
As there are rarely any valves in the hypogastric veins, the blood 
from the viscera and hind-limbs can pass freely either through the iliac 
veins and thence to the inferior vena cava, or through the coccygeo- 
mesenteric vein to the hepatic portal system. 
The epigastric vein of the bird takes blood from the fat-laden sheet 
or great omentum which covers the abdominal viscera. It leads not 
into the liver, but into one of the hepatic veins. - 
Associated with the blood-vascular system there is a 
lymphatic system with a few lymphatic glands. 
The spleen lies on the right side of the proventriculus, the 
paired thyroid lies beside the origin of the carotids, and a 
paired thymus is found in young birds in the neck region. 
Small yellowish (suprarenal) glands lie on the front part of 
the kidneys. 
