192 ANATOMY OF VERTEBRATES. 



and supplies the marsupial membrane; the second plexus, ib. 4, 

 is situated more exteriorly, and gives off the ciliary arteries. 



After the carotid has sent off the entocarotid, it passes for a 

 little way downward and forward behind the angle of the jaw, and 

 divides at once into different branches, corresponding to those of 

 the ectocarotid in Mammals ; the first of which might be called the 

 oesophageal or laryngeal artery. This vessel sends a branch to 

 the muscles upon the thyrohyal, and then turns downward and 

 divides into two branches, one to the trachea, fig. 93, G i, and the 

 other to the oesophagus, upon the side of which parts they descend 

 to near the thorax, forming a series of arches, ib. ii, ii, and ulti- 

 mately inosculate with the tracheal and oesophageal branches of 

 the common trunk of the carotid and vertebral arteries. 



The external maxillary artery, ib. 12, dips in between the 

 pterygoid and digastric muscles ; it then passes behind the tym- 

 panic, and gives twigs upAvard to the muscles of the jaws, and 

 to the plexus at the back of the orbit: upon emerging from 

 behind the tympanic, it lies under the zygomatic arch, and sends 

 an artery upward, which is distributed to the temporal and mas- 

 seter muscles, and proceeding under the triangular tendon that 

 comes from the inferior margin of the orbit to the lower jaw, it 

 divides into two principal branches ; one of these passes along the 

 side of the upper jaw, gives a branch upward to the fore part of 

 the orbit which unites with the ophthalmic artery, and is lost at 

 the top of the head. This branch is very large in birds with 

 combs, as, in conjunction with the ophthalmic, it furnishes nu- 

 merous vessels to these vascular parts. The artery then goes on 

 and supplies branches to the sides of the head before the orbits, 

 and to the integuments and substance of the upper mandible, 

 inosculating mth the palatine branches of the internal maxillary 

 artery. The second portion of the external maxillary proceeds to 

 the lower jaw, to which, and the lower part of the masseter muscle, 

 it is distributed. The external maxillary supplies the place of the 

 temporal, labial, angular, nasal, and mental arteries of mammals. 



The laryngeal or j^osterior palatine artery is a little branch of 

 the ectocarotid, which is sent off posteriorly opposite to the ex- 

 ternal maxillary artery. Its branches are exhausted upon the 

 back part of the fauces, the muscles for moving the upper jaw, 

 and posterior nares. 



The lingual or submaxillary artery, ib. 13, passes under the 

 muscles which connect the hyoid to the lower jaw, and close upon 

 the back of the membrane of the lower part of the mouth, it sends 

 a branch to the oesophagus and trachea, supplies the muscles 



