CHAP, viz.] THE CAT'S ORGANS OF CIRCULATION. 207 



side ^of the head. The four posterior branches are the iliac 

 arteries already referred to. Besides the aortic arch, the rest of its 

 course, which is called the descending aorta, is sub-divided into the 

 part in front of the diaphragm and the part below it i.e., into the 

 thoracic and the abdominal aorta. 



The arch of the aorta gives off, almost from its very starting 

 point as before mentioned the coronary arteries (which go I to 

 the heart itself), and afterwards the four great vessels (which 



Fig. 104. THE HEART, GREAT VESSELS AND LUNGS OF THE CAT ; VENTRAL ASPECT. 



Ao. Arch of aorta. 

 CC. Carotid arteries. 

 Da. Ductus arteriomis. 

 LA. Left auricle. 

 LV. Left ventricle. 

 PA. Pulmonary artery. 

 RA. Right auricle. 

 RV. Right ventricle. 

 T. Trachea. 

 IV. Vena cava inferior. 



VS. Vena cava superior. 

 Vc. S. Vena azygos. 



1. Upper lobe of right lung. 



2. Second lobe of right lung. 

 8. Third lobe of right lung. 



4. Fourth or lowest lobe of right lung. 

 4a. Partly separate portion of fourth lobe. 



5. Upper lobe of left lung. 



5. Partly separate portion of the same. 



6. Lower lobe of left lung. 



go to the head and fore-limbs) by two very unequal trunks. One of 

 these, the larger, and placed on the right, is called the innominate 

 artery. (Fig. 102, n.) It soon gives off a large branch (cl), which is 

 the left carotid artery ; and the remaining part, almost immediately 

 bifurcates into the right carotid and the right sub-daman arteries. 



