134 GENERAL BIOLOGY. 



posite side, but runs anteriorly to about 

 the level of the left renal vein. In this 

 case the left spermatic vein empties into 

 the ilio-lumbar vein. 



6. The external iliac veins, bringing blood from 



the legs, from the bladder, and in the 

 female from the uterus. 



7. The internal iliac veins, which by their union 



form the posterior vena cava. They bring 

 blood from the postero-dorsal part of the 

 thighs. 



II. The Portal System. 



The portal vein enters the liver by a branch 

 to each lobe. (It is formed by veins from 

 the stomach, from the different regions of 

 the intestine, and from the spleen.) 



III. The Pulmonary Veins. 



(These are best seen when taking out the 

 heart and lungs, IV. C.) Two veins from 

 each lung which enter the dorsal side of 

 the left auricle. 

 B. The Arteries. 



I. The aortic arch, arising from the left ventricle 

 and curving to the left to form in the median 

 dorsal line the dorsal aorta. 

 The aorta gives off the following arteries : 

 1. Near the beginning of the arch, a vessel to 

 the right, the innominate artery, which soon 

 divides to form : 



