Chap. III.] GENERAL ANATOMY. 41 



the heart to the left ; it is the pulmonary artery (p. a.) carrying 

 blood to the lungs. Another thick-walled artery arises rather 

 to the right of this (but from the left ventricle), and after 

 giving off branches (common carotid) which may be traced 

 upwards beside the trachea to the head, and branches to the 

 arms, of which that on the right side is given off from the 

 right carotid (r. c.), passes back over (dorsal to) the heart. It 

 is the aortic arch (ao. ar.\ of which there is but one in the 

 rabbit. It curves over to the left, crossing the left bronchus, 

 and represents the left aortic arch of the frog. As it passes 

 along the roof of the peritoneal cavity, the thick-walled pink 

 aorta (ao.) gives off renal branches to the kidneys, three to the 

 stomach and intestines, one in front of and two behind the renal 

 arteries, and finally divides into two branches (18, com. il. a.) 

 for the hind-limbs. 



Close by this pink thick-walled empty aorta will be seen the 

 larger thin- walled postcaval vein (pt. c.). This carries blood to 

 the right auricle of the heart from the posterior parts of the body, 

 and from the kidneys, to which there passes no renal portal 

 vein. The postcaval shortly before reaching the heart receives 

 the hepatic vein from the liver, which conveys from that organ 

 not only the blood received from the hepatic artery, but the much 

 larger quantity delivered to it from the stomach and intestines 

 by the portal vein. The right auricle, which receives the post- 

 caval vein from the posterior regions of the body, receives also 

 precaval veins (r. pr. c.) from the head and anterior regions. Of 

 these precavals the large (external jugular, ex. ju.) veins seen on 

 each side of the trachea, the smaller (internal jugular) veins lying 

 still closer to the trachea, and large (subclavian, s. cl.) veins from 

 the arms are factors. 



The left auricle receives, by pulmonary veins (p. v.\ the blood 

 which has passed through the capillaries of the lungs. 



The distribution of the vessels will be seen by reference 

 to Figs. 17 and 18, and will be more fully considered in 

 Chapter X. 



4. The Urmo-genital System. The kidneys, which have the 

 characteristic mammalian form, are attached to the body-wall 



