THE CIRCULATORY SYSTEM 83 



arteries enter the anterior lobe of the kidneys. 

 The femoral and sciatic arteries pass into the 

 leg, the latter also supplying the middle and 

 posterior lobes of the kidney. A single caudal 

 mesenteric artery goes to the rectum and 

 cloaca, and a pair of hypogastric arteries supply 

 the walls of the pelvis. The aorta terminates 

 as a single caudal or middle sacral artery which 

 passes into the tail. 



The Veins (Fig. 48) 



Each lung is drained by a pulmonary vein 

 which joins its fellow just before reaching the 

 left atrium into which they open in common. 

 The blood from the rest of the body is carried 

 to the right atrium by the three venae cavae. 

 Each of the two cranial venae cavae is formed 

 by the union of a jugular vein, which drains the 

 head and neck, and a subclavian vein correspond- 

 ing to the artery of the same name. 



The comparatively short caudal vena cava 

 is formed by the union of the right and left 

 common iliac veins just cranial to the kidneys. 

 It runs towards the heart, buried more or less 

 in the right lobe of the liver, and opens into 

 the right atrium. Hepatic veins convey the 

 blood from the liver into the vena cava, and 



