240 THE BIOLOGY OF THE ANIMAL 



c. The pulmonary veins. — Turn the heart for- 

 ward and find coming from each lung a small, 

 dark-colored vein. What is their position with 

 regard to the sinus venosus? "Which cavity of 

 the heart do these veins enter? Do they unite 

 before entering the heart? 



Make a drawing showing the relation of the pulmo- 

 nary veins to the heart. 



d. The anterior abdominal vein. — Examine the 

 median ventral line of the body. "What is the 

 course of this vein ? Note its branches, the epi- 

 gastric veins. How are they arranged ? How are 

 they situated with regard to the abdominal mus- 

 cles ? Trace the anterior abdominal vein back to 

 the pubis, and note that it is formed by the union 

 of two short veins, the pelvic veins. Separate 

 the muscles of one of the thighs and find the two 

 veins, femoral and sciatic, which unite to form 

 the pelvic vein. The femoral vein may be distin- 

 guished by its larger size. Does this vein com- 

 municate with the sciatic? Trace the femoral 

 vein to the space back of the knee-joint, and note 

 that this vein is a continuation of another, the 

 posterior tibial vein, which arises from branch- 

 es covering the upper surface of the foot. At 

 the posterior end of the anterior abdominal vein 

 find the vesical vein, coming from the bladder. 

 Look also for the parietal veins, which come 

 from the ventral side of the body-wall. On the 

 truncus arteriosus find another branch, the car- 

 diac vein. At the forward end of the anterior 

 abdominal vein find its branches, which run to the 

 liver. Does this vein communicate directly with 

 the heart ? 



