Chap. X.] 



THE HEART AND CIRCULATION. 



207 



to the right so as to be visible near its origin passing behind the 

 ilio-lumbar vein. It passes backwards to the pelvis and tail, 

 and is the direct continuation of the dorsal aorta, answering to 

 the caudal artery in the fish. 



The veins returning blood from the pelvic region and hirid- 



FIG. 64. PELVIC VESSELS RABBIT. 



com. il. a., com. il. v. Common iliac artery and vein. ex. il. a., ex. il. v. Ex- 

 ternal iliac artery and vein. fern, a., fern. v. Femoral artery and vein. in. il. 

 a., in. il. v. Internal iliac artery and vein. il. 1. a., il. I. v. Ilio-lumbar artery 

 and vein. m. s. a. Median sacral artery, p. m. a. Posterior mesenteric 

 artery, pt. c. Postcaval vein. sp. a. , sp. v. Spermatic artery and vein. 



limb will be understood by a study of a careful dissection, aided by 

 the figure. The internal iliacs unite into a common trunk, which 

 is successively joined by thefemorals, ilio-himbars, and spermatics. 



The blood is conveyed from the stomach and intestines by a 

 portal system to the liver. The portal is composed of (1) a large 

 anterior mesenteric vein, which receives a small posterior mesenteric 

 (from the rectum) ; and (2) a lieno-gastric vein from the stomach 

 and spleen. 



Turn now to the heart itself. The auricles are thin- walled, 

 especially in the atrial portion lying dorsally. Those portions 

 which project over the base of the ventricles and are visible in 



