ARTERIES OF BIRDS. 199 



branch, soon after it leaves the trunk of the superior mesenteric, 

 divides into two. One descends upon the rectum, where it meets 

 with the inferior mesenteric artery, with which it produces a very 

 remarkable anastomosis, similar to the mesenteric arch in the 

 human subject ; this united artery supplies the rectum and origin 

 of the coeca. The second portion of this branch of the superior 

 mesenteric runs in the space between the last part of the small 

 intestine and the coecum of one side, sending numerous branches 

 to each, and at the end of the ca3cum communicates in a palpable 

 manner with another branch of the superior mesenteric artery, 

 which runs upon the adjoining part of the small intestine. 



^ A branch, arteria spermatica, fig. 93, 22, arises from the 

 anterior part of the aorta, just below the lungs ; it is designed 

 for the nutrition of the organs of generation, and except in the 

 season for propagation, it is so small as to be discovered with 

 difficulty ; but when the testicles become enlarged, it is consider- 

 ably increased in size in the male bird, and much more so in the 

 female, when the ovary and OAdduct are developed for producing 

 eggs. It nearly equals the superior mesenteric artery during the 

 period of laying, in which state we shall describe it. It is a 

 single artery, like the coeliac and mesenteric, proceeds at a right 

 angle from the aorta, and soon sends off" a branch, which goes 

 into the kidney of the left side, to which it gives some twigs, and 

 afterwards emerging from the kidney, it runs in the membrane of 

 the o\dduct, upon Avhich it is distributed. After this branch is 

 detached, the artery projects a little farther forward into the 

 cavity, and divides into two branches ; one of these goes to the 

 ovary, in which it ramifies, and furnishes an artery of some size 

 to each of the cysts containing the ova. The other is distributed 

 in numerous branches to the membrane and superior parts of the 

 oviduct, and inosculates with the other arteries of the oviduct. 

 It deserves to be remarked, that this and all the other arteries 

 which are furnished to the oviduct have a tortuous or undulating 

 course, in the same manner as the vessels of the uterus of the 

 human subject. 



' There are no regular emu! gent arteries in birds ; the kidneys 

 deriving their blood from various sources, which will be pointed 

 out as they occur. 



' The inferior extremity is supplied with two arteries, which 

 have a separate origin from the aorta. One corresponds to the 

 femoral, and the other to the ischiadic artery. 



' The femoral artery, figs. 93, 94, 23, is a small trunk, which 

 takes its origin from the side of the aorta, opposite to the notch 



