142 



ELEMENTS OF MAMMALIAN ANATOMY. 



divides this auricle from the adjoining one is an oval 

 depression, the fossa ovalis, where, in the embryo, the 

 two auricles communicated. The left auricle is in con- 

 tact with the right dorsally, and receives three pulmonary 

 veins (Fig. 69). 



FIG. 68. VENTRAL ASPECT OF THE 

 HEART WITH ITS CAUDAL THIRD 

 CUT OFF TRANSVERSELY. 



a, Adipose tissue; be, brachioceph- 

 alic artery ; la, left auricle ; Iv, left 

 ventricle; Ic, left carotid artery; 

 o, ductus arteriosus ; pv, pulmon- 

 ary vein ; ba, pulmonary artery ; 

 pc, precava; psc, postcava; ra, 

 right auricle ; re, right carotid ar- 

 tery ; rs, right subclavian artery ; 

 rv, right ventricle; sb, left subcla- 

 vian artery; tr, trachea. 



FIG. 69. DORSAL ASPECT OF THE 

 HEART OF THE CAT. 



ao, Aorta ; ap, apex ; as, azygos vein ; 

 be, brachiocephalic artery; ca, 

 coronary artery; cv, coronary 

 vein; /, left auricle; Ic, left caro- 

 tid artery; Isb, left subclavian ar- 

 tery ; p, postcava ; pc, precava ; pa, 

 pulmonary artery dividing into 

 its right and left branches ; ra, 

 right auricle; re, right carotid; 

 rs, right subclavian ; v, pulmonary 

 veins. 



From the right ventricle arises the pulmonary artery 

 which carries the impure blood to both lungs. Its 

 mouth is guarded by three semilunar valves which 

 prevent the return of the blood. The left ventricle gives 

 origin to only one important vessel, the aorta, which 

 arches dorsally around the left auricle, and at the apex 



