THE VASCULAR SYSTEM. 131 
margins of the translucent membranous valves to the 
columnze carneze or muscular projections on the walls of 
the ventricles. The walls of the auricles are thin in com- 
parison with the walls of the left ventricle, which are twice 
as thick as the walls of the right ventricle (Fig. 70). 
The auricles are very small when not injected, and may 
DorsAL ASPECT OF THE 
Fig. 71. 
HEART OF THE Cart. 
Fic. 70. WENTRAL ASPECT OF THE 
Heart witH 1Ts CaupaL THIRD 
Cur orr TRANSVERSELY. 
a, Adipose tissue; bc, innominate 
artery; la, left auricle; lv, left 
ventricle; /c, left carotid artery; 
o, ductus arteriosus; pv, pul- 
monary vein; ba, pulmonary 
artery; pc, superior vena cava; 
psc, inferior vena cava; ra, 
right auricle; rc, right carotid 
artery; rs, right subclavian 
artery; rv, right ventricle; sb, 
left subclavian artery; tr, tra- 
chea. 
ao, Aorta; ap, apex; as, azygos 
vein; bc, innominate artery; 
ca, coronary artery; cv, coro- 
nary vein; J, left auricle; Ic, 
left carotid artery; /sb, left sub- 
clavian artery; pf, inferior vena 
cava; pc, superior vena cava; 
pa, pulmonary artery dividing 
into its right and left branches; 
ra, right auricle; rc, right ca- 
rotid; rs, right subclavian; v, 
pulmonary veins. 
by the beginner be cut away with the pericardium and sur- 
rounding adipose tissue. The right auricle receives three 
veins, the superior vena cava, inferior vena cava and coro- 
nary veins, all of which enter its dorsal aspect. The portion 
