212 The Alligator and Its Allies 



The Arterial System 



The Abdominal Aorta and its Branches. The 

 right and left aortic arches, Fig. 6i, Aod, Aos, 

 arising from the heart in the manner already 

 described, form a rather long loop and approach 

 each other in the middorsal line. Here they are 

 united by a short, wide connective in such a way 

 that the left arch seems continued into the coeliac 

 artery and the right into the dorsal aorta proper. 

 Each arch, anterior to the connective, gives off two 

 fairly large branches, oe, to the posterior region of 

 the oesophagus. 



The c<3?/^'ac artery. Fig. 6i, c, is the largest branch 

 of the abdominal aortic system. After giving off a 

 couple of small branches, oe, to the posterior region 

 of the oesophagus, it gives off a large splejio-intesti- 

 nal artery, si, to the spleen and small intestine. 



The coeliac then breaks up into three arteries 

 of about the same size: the gastro-hepatico-intesti- 

 nal, ghi, carrying blood to the stomach, liver, and 

 small intestine; the pancreo-intestinal, pi, leading 

 to the pancreas and small intestine ; and the gastric, 

 ga, to the greater part of the stomach. 



From the dorsal aorta proper, da, which, as has 

 been said, seems to be the direct continuation of 

 the right aortic arch, several arteries are given 

 off; these will be described as they occur in an 

 antero-posterior direction. 



At about the point of union of the two aortic 



