THE BABBIT. 133 



10. Observe on each side of the neck the dark jugular 

 ye in running back toward the heart ; note that each 

 of these is formed by two main branches, the external 

 and internal jugular veins, which unite just back of 

 the head. 



11. Just before each jugular vein enters the chest-cavity 

 it receives a branch from the corresponding fore 

 limb; these are the subclavian veins. The union of 

 the jugular and subclavian veins on each side forms 

 the vena cava superior. 



12. Trace the right vena cava superior straight back to 

 the right auricle. Turn the heart forward and follow 

 the course of the left vena cava superior in reaching 

 the same auricle. 



13. The large vena cava inferior, coming forward through 

 the diaphragm to the right auricle, is easily seen. 



The heart and lungs may now be removed, and the 

 pulmonary artery and veins traced, and the structure 

 and action of the heart made out by the following 

 directions ; but the heart and lungs of the pig, calf, 

 or sheep will show the same features much better on 

 account of their greater size. 



THE HEAD OF THE RABBIT. 



Remove the skin from the head. 

 1. Below and back of the ear is an irregular pink mass, 

 the parotid salivary gland. The duct which con- 

 veys its secretion runs forward and opens on the 

 inside of the cheek. It is hard to trace in the rabbit. 

 Find it in the dog, slit into it with fine scissors, and 

 push a bristle forward through it to find its opening 

 in the mouth. 



