ARTEKIES OF BIRDS. l98 



of the hyoicl, ib. F, the tongue, E, the lower surface of the mouth, 

 and furnishes the artery which enters the substance of the lower 

 jaw. 



' Just at the origin of the submaxillary artery there is another 

 little branch of the carotid, which is lost upon the muscles of the 

 hyoid arch. 



' The internal maxillary artery is, as usual, the continuation 

 of the trunk of the ectocarotid; it runs forward between the 

 pterygoid muscle and the lining of the mouth, upon the side of 

 the long muscle for moving the upper jaw, and divides into two 

 principal branches; one of them proceeds under the tendon of 

 the long muscle to get upon the palate, where it forms two 

 branches, of a\ hich one runs along the external side of the palate, 

 between the membrane and the bone of the mandible to the 

 extremity of the bill, where it becomes united to the same branch 

 of the opposite side, as also to the middle artery of the palate. 

 The other branch lies also superficially under the membrane 

 which lines the mouth. It passes onward to meet its correspond- 

 ing vessel of the opposite side, with which it becomes actually 

 incorporated, and by their union a single artery is generated, 

 which runs along the middle line of the palate to the end of the 

 mandible, where it unites mth the lateral branches, as already 

 mentioned. At the junction of the vessel of each side to form 

 the middle palatine artery, two branches go off, which are lost upon 

 the lining of the mouth, and the interior of the organ of smell. 



^ The other branch of the internal maxillary artery is reflected 

 upward toward the orbit, below which it divides and unites again, 

 forming a triangle, through which the vein passes : at this place 

 it produces a remarkable plexus of vessels, like the rete mirabile 

 of the carotid artery of quadrupeds, which is increased by branches 

 from the ophthalmic and the palatine arteries, and from which the 

 back part of the organ of smell receives its supply of blood. 



^ The internal maxillary artery then runs directly backward 

 below the orbit, passes between the radiated or fan-shaped muscle 

 which moves the upper jaw and the pterygoid ; and turning- 

 inward round the basis of the cranium, becomes incorporated with 

 the internal carotid artery just as it enters the bony canal which 

 conducts it to the brain. ^ 



' The vertebral artery, fig. 93, 6, soon after it parts from the 



' Barkow describes the internal maxillary artery as wanting in birds, and its place 

 being supplied by branches of both the external and internal carotids and the facial 

 artery, all of which sometimes unite to form the maxillary plexus of vessels, which is 

 very conspicuous in the Goose and Duck. xliv. 

 VOL. II. O 



