200 



THE CAT. 



[CHAP, vn. 



are called auricles, and the other two, ventricles one of each on 

 each side. The auricle and ventricle of the right side are com- 

 pletely divided off from those of the left side. The auricles open 

 into the ventricles by valvular apertures, and valves guard the 

 openings of the great vessels. 



Such being a summary of its main characters, its various parts 

 need examination in detail. 



The heart of the cat lies on the ventral side of the body, within 



cr 



cl 



si 



TVLV 



Fie. 102. CAT'S HEART CUT OPEN. 



A. The left side. 



B. The right side. 



a. Style passing up through inferior vena cava 



to right auricle. 

 AO. Aorta, 

 fo. Style passing down from the vena azygos 



through superior vena cava into right auricle. 



c. Style passing down from the superior vena 



cava into the right auricle. 

 CA. Conus arteriosus. 

 cl. Left carotid. 

 cr. Right carotid. 



d. Style passing from conus arteriosus into left 



branch of pulmonary artery. 

 /. Style passing up from left ventricle into 



aorta. 

 FO. Place where the foramen ovale existed in 



the foetus. 



g, h, i. Styles passing through pulmonary vein 



into left auricle. 

 LA. Left auricle. 

 LV. Left ventricle. 

 MV. Mitral valve. 

 n. Innominate artery. 

 PAL. Left branch of pulmonary artery. 

 PAR. Right branch of pulmonary artery. 

 RA. Right auricle. 

 RV. Right ventricle. 

 si. Left sub-clavian artery. 

 SLV. Semi-lunar valve. 

 sr. Right sub-clavian artery. 

 TL. Tubercle of Lower. 

 VCI. Inferior vena cava. 

 VCS. Superior vena cava. 



the thorax, upon the inner surface of the sternum and between the 

 two lungs. It is almost globular in shape, but slightly narrows 

 towards its posterior end or apex, which touches the anterior 

 surface of the diaphragm. 



At its opposite end, or base, the heart is connected with several 

 great blood-vessels, but elsewhere its surface is free. 



The pericardium is a bag of dense fibrous tissue with an epithelial 

 lining, and contains like the peritoneum a serous fluid. This 



