AVES. 



333 



processes of the cervical vertebrae, within which 

 it lies hidden, and in close contact with its fellow 

 of the other side, to very near the head." In 

 the Bittern the two carotids are situated one 

 behind the other, and adhere so intimately to- 

 gether in this situation that they have been 

 erroneously described as a single trunk. 



" The carotid artery emerges from between 

 the muscles of the neck, at about the third or 

 fourth vertebra from the head (9) ; and after 

 giving a branch (10, 11), Arteria' cutancte colli 

 laterules, downwards, to the lateral muscles and 

 integuments of the neck, it runs along the outer 

 edge of the rectus major anticus muscle to behind 

 the angle of the jaw, where it divides into its 

 several branches. 



" An artery (arteria occipitalis) first goes off 

 posteriorly, which passes a little forwards under 

 the branch of the os hyoides, and after sending 

 some blood to the muscles of the neck, makes 

 a turn backwards, enters the foramen in the 

 transverse process of the second vertebra, and 

 terminates by a singular anastomosis in the 

 vertebral artery.* 



" The next branch is analogous to the internal 

 carotid; it goes forward also under the os 

 hyoides, and passes behind the muscles of the 

 jaws close upon the lower part of the skull, at 

 which place it sends a branch upwards, which 

 appears to penetrate the bones on the outside 

 of the ear, and supply the organ of hearing, 

 sends a branch into the skull and another 

 through the articulation of the jaw, to unite 

 with the ophthalmic, and contribute to the 

 plexus at the back of the orbit (Rete oph- 

 thalmicum of Barkow). The internal carotid 

 then enters an osseous canal, which runs 

 along the basis of the cranium, between the 

 tables of the bone ; and at the lower and 

 back part of the orbit, the artery receives a 

 remarkable anastomosing branch of the inter- 

 nal maxillary, which almost equals in size the 

 carotid itself, and these two vessels produce 

 by their union one which passes almost directly 

 into the cranium at the usual place for the 

 entrance of the carotid artery. This vessel 

 forms within the skull an anastomosis similar 

 to the circle of Willis; but the branch which 

 occupies the place of the basilar artery is very 

 small, and appears to be furnished entirely 

 from the anastomosis of the carotids, and do- 

 signed only to supply the medulla oblongata 

 and spinal marrow. The branches of the in- 

 ternal carotid are thickly spread in an arborescent 

 form upon the surfaces of the brain ; some on 

 the outside and others on the internal super- 

 ficies of the ventricles, and the fissure between 

 the two hemispheres." Theorbital plexus formed 

 by the carotid sends off the inferior palpebral, 

 ethmoidal, lachrymal, and ophthalmic arteries. 

 The ophthalmic artery forms two remarkable 

 plexuses at the posterior part of the globe of the 



* Dr. Barkow has subsequently established the 

 accuracy of this observation, having found this 

 singular anastomosis of the occipital with the ver- 

 tebral artery in all the birds which he has injected. 

 Tiedemann is therefore inaccurate in saying that the 

 vertebral artery has the same termination in birds 

 as in man. 



eye ; the first is situated close beside the inner 

 side of the optic nerve, and is formed by an 

 artery analogous to the arteria centralis retime, 

 and gives off the artery to the base of the 

 marsupial membrane; the second plexus is 

 situated more exteriorly, and gives off the ciliary 

 arteries. 



"After the trunk of the carotid has sent off the 

 internal carotid, it passes for a little way down- 

 wards and forwards behind the angle of the jaw, 

 and divides at once into different branches, cor- 

 responding to those of the external carotid in 

 mammalia ; the first of which might be called 

 the oasophageal or laryngeal artery. This vessel 

 sends a branch to the muscles upon the horn 

 of the os hyoides, and then turns downwards 

 and divides into two branches, one to the 

 trachea (G,fig. 170), and the other to the oeso- 

 phagus, upon the side of which parts they 

 descend to near the thorax," forming a series of 

 arches (11, 11), and ultimately inosculate with 

 the tracheal and oesophageal branches of the 

 common trunk of the carotid and vertebral 

 arteries. 



" The external maxillary artery (12) dips in 

 between the pterygoid muscle and that which is 

 situated at the back of the lower jaw for open- 

 ing the mouth ; it then passes behind the 

 tympanic bone, and gives twigs upwards to the 

 muscles of the jaws, and to the plexus at the 

 back of the orbit : upon emerging from behind 

 the tympanic bone, it lies under the zygo- 

 matic or jugal bone, and sends an artery up- 

 wards, which is distributed to the temporal 

 and masseter 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 upwards 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 con- 

 junction with the ophthalmic, it furnishes 

 numerous 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 with 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 mammalia. 



" The laryngeol or posterior palatine artery is 

 a little branch of the external carotid, which 

 is sent off posteriorly opposite to the external 

 maxillary artery. Its branches are exhausted 

 upon the back part of the fauces, the mus- 

 cles for moving the upper jaw, and posterior 

 nares. 



" The lingual or submaxillary artery (13) 

 passes under the muscles which connect the os 

 hyoides 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 resophagus and trachea, 

 supplies the musc'es of the os hyoides (F), 



