216 The Alligator and Its Allies 



leg. After giving off the fibular and tibial arteries, 

 the sciatic passes, as a large vessel, through the 

 lower leg, to which it gives but few branches, and 

 may here be called the crural artery, cr. At the tar- 

 sus it divides rather suddenly and, perhaps, vari- 

 ably, into four chief branches, leading to the toes. 



A short distance caudad to the origin of the iliacs 

 the dorsal aorta gives off a pair of small pelvic arter- 

 ies, pa 1 , going to the muscles of that region. Cau- 

 dal to these pelvic arteries is given off the unpaired 

 first hcemorrhoidal artery, he 1 , which divides into a 

 rectal, rt 1 , and a cloacal, cl, branch. 



Caudal to the first hasmorrhoidal arises the second 

 hcemorrhoidal, he 2 ; also unpaired, leading to the 

 cloaca. 



Posterior to the second hasmorrhoidal, the aorta 

 continues into the tail as the large caudal artery, ca. 



The A nterior A rteries. The origin of the great ar- 

 terial trunks the pulmonary, aortic arches, primary 

 carotid, and right subclavian has already been given 

 and the distribution of the pulmonary arteries and 

 aortic arches has been described, so that it now re- 

 mains to describe the distribution of the right sub- 

 clavian, Fig. 62, sc.d., and the primary carotid, capr. 



The right subclavian, sc.d., since it has an 

 independent origin from the heart, instead of aris- 

 ing as a branch of the primary carotid, will be 

 described first. After leaving the heart it passes 

 cephalad and laterad and gives off the following 

 branches in order, beginning at the heart: an 



