366 CHORD AT A. 



jugulars anastomose together below the tongue. The post- 

 caval can be traced backwards through the liver where it 

 receives paired hepatics. A little way behind the liver it 

 diverges into two iliac veins. The portal vein may be seen 

 passing to the liver from the stomach and intestine. Its 

 most posterior branch, the posterior mesenteric, anastomoses 

 with the systemic system (see below). 1 he portal has the 

 same relationships as in the skate and frog, but there is no 

 anterior abdominal. 



The epigastric vein is said to represent this vein. It drains the 

 omentufn, a fatty fold of peritoneum, and runs forward to join the 

 left hepatic vein. 



If the rectum be cut through and the intestine carefully 

 removed, the veins and arteries in the abdominal region will 

 be easily seen (see Plate IX.) They are in relation to the two 

 large three-lobed kidneys, lying in a hollow of the pelvis. 



From the tail there emerges a small caudal Yom which 

 bifurcates into two renal portals diverging right and left 

 towards the kidneys. Each receives an internal iliac and 

 then passes through the kidney. Between the second and 

 third lobe of the kidney, the renal portal receives the sciatic 

 and between the first and second it receives a IdiXgQ femoral 

 The femoral and sciatic then form the iliac w^hich receives 

 a re7ial from the kidney, and then unites with its fellow to 

 form the postcaval. Hence the iliacs and renal portals 

 form a complete " renal cycle " running left and right from 

 caudal to postcaval. 



At the point of junction of caudals and renal portals 

 there runs forward beside the rectum a large median vein, 

 the posterior mesenteric. It joins the portal anteriorly. 



The arterial system consists, like the venous, of two 

 parts. (i) The right ventricle gives off a trunk which 

 immediately bifurcates into two pulmonary arteries going to 

 ResDirator ^^ lungs. These correspond to the third 

 arterial arches (pulmocutaneous) of the frog. 

 (2) The systemic system — the left ventricle 

 gives off a main trunk which divides into three. Two 

 are paired and anterior ; they are called the innominate 

 arteries and divide into carotid to the head and sub- 

 clavian which itself divides into brachial and pectoral. 

 The third bends over to the right and passes dorsal to the 



