460 



Anat(iiiiy and r)!'^'!^}!!!!*'!!! of N'oins of Clicloiiia 



The revehent system consists of the postcava, the left hepatic i-evohent 

 vein, and several smaller veins, all of which open separately into the sinus 

 venosus. 



The largest of the revehent veins is the hepatic postcava. It passes 

 directly through the right superior lobe of the liver and, after receiving 

 a number of branches from this organ, opens into the right side of the 

 sinus venosus. The largest of its hepatic tributaries is the right hepatic 

 vein which usually opens into the postcava where the latter joins the 

 sinus venosus. 



The other large vein which opens into the sinus venosus is the left 

 hepatic revehent vein. 



Besides these two large veins, a number of smaller ones open directly 



RIGHT HEPATIC AOVEHENT 



PRECAVA 



SINUS VENOSUS 



RIGHT ABOOMIN 



MESENTERIC PORTAL fljj ..,, 



GASTRIC VEIN 



S. LEFT ABDONIINAL 



Fig. 1. Hepatic portal system of Kinosternon pennsylvanicum. Ventral 

 view. 



into the sinus venosus from the liver. The number of these is not con- 

 stant, but depends, as we shall see when we come to study their develop- 

 ment, upon the relative backward extension of the venous sinus. 



The advehent system consists of the two abdominal and the portal 

 veins. 



The abdominal veins (see also Fig. 10) arise as branches of the circum- 

 flex iliac of each side and extend mediad and craniad for a short dis- 

 tance along the cranial border of the ventral segment of the pelvic 

 girdle. Just in front of the apex of the triangle formed by the union 

 of the two pubic bones, the two abdominals are connected by a short 

 anastomosing branch. From this point they continue forward along 

 the abdominal wall as separate vessels and then enter the liver. 



The left abdominal vein is much larger than the right. It passes 

 dorsad through the left inferior lobe of the liver to its gastro-duodenal 



