ARTEKIES OF BIRDS. 197 



appears to send ofF arc hronchial arteries ; they arise from the 

 fore part of tlie aorta, just when it arrives upon the spine ; and 

 having entered the kings, tlieir ramifications accompany those 

 of the puhnonary arteries. They appear also to send branches 

 to the spine and the spaces between the ribs. 



* The intercostal arteries do not take their origin from the aorta 

 in numerous and regular branches as in Mammals, but consist 

 originally of but few vessels, which are multiplied by anasto- 

 moses with each other, and with the arteries which come out of 

 the spinal canal. An arterial plexus is thus formed round the 

 heads of the ribs, from which a vessel is sent to each of the inter- 

 costal spaces. Many of these branches, besides supplying the 

 intercostal muscles and ribs, are continued into the muscles upon 

 the outside of the body and the integuments. The anastomosis 

 of the intercostal arteries round the ribs is very similar to the 

 plexus, which is produced by the great sympathetic nerve in the 

 same situation. 



' The aorta produces no branch which deserves the name of 

 the j)hrenic artery, as birds do not possess that muscular septum 

 of the body to which the artery of this name is distributed in 

 other animals. 



* The cceliac artery, fig. 93, 20, is a very large single trunk, and 

 arises from the fore part of the aorta, even higher than the zone 

 of the gastric glands. It descends obhquely for a short way, and 

 then ffives off a branch which soon divides into two or three 

 others that are spread upon the lower part of the oesophagus, and 

 the side of the zone of the gastric glands, uniting with the other 

 arteries of the oesophagus above, and extending downwards upon 

 the posterior side of the ventricle, and anastomosing with the 

 anterior gastric artery. The trunk of the eoeliac now di\ides into 

 two very large branches, which from their distribution we have 

 chosen to call the posterior and the anterior gastric arteries. 



' The posterior gastric artery, almost as soon as it is formed, 

 detaches the splenic artery ; and very soon after it furnishes from 

 the posterior side of the vessel the right hepatic artery. This 

 branch proceeds to the right lobe of the liver, which it enters on 

 the side of the hepatic duct ; after having divided into two or 

 three minute arteries on its way to the liver, it supplies the 

 hepatic duct with a branch which accompanies the duct to the 

 intestine, and is there lost. The posterior gastric artery then 

 runs down upon the back of the gizzard, and opposite to the 

 origin of the first intestine it sends off an artery, Avhich proceeds 

 directly to one of the cocca (in the Fowl), upon which and the 



