CIRCULATORY SYSTEM OF THE GRASS-SNAKE. 639 



immediately divides into two fairly ec[uisized terminal brandies. 

 On its way it gives off : — 



I. A branch (Ramus glandules maxillse superioris posterior, 

 Sclilemm) which arises a short distance behind the orbit and runs 

 outwards to the posterior part of the parotid gland, i. e., the gland 

 corresponding to the poison-gland of other snakes. It ramifies 

 in the gland, and one of its branches anastomoses with a branch 

 of the artery suppljdng the anterior part of the gland. During 

 its course it gives off a palatine branch and branches to several 

 muscles. 



II. Several siiiall branches and one fairly well-marked one that 

 supply the Harderian gland. 



III. Two or three slender branches to the skin overlying the 

 skull and one or two to the under side of the skull. 



One terminal branch (Oarotis facialis, Schlemm) of the facial 

 carotid passes along the back of the orbit downwards to its floor, 

 where it runs forward (Ramus palatinus anteiior, Schlemm), 

 accompanying the infra-orbital branch of the trigeminal nerve. 

 It goes on forward out of the orbit, close to the outer wall of the 

 internal nares, and finally spreads out over the skin and muscles 

 at the front end of the snout. During its course it gives off: — 



I. A well-marked vessel (Ramus glandulse maxillaris superioris 

 anterior, Schlemm) that accompanies the supra-maxillary branch 

 of the trigeminal nerve outwards in the posterior wall of the 

 orbit and along the upper jaw. It supplies the teeth in the pos- 

 terior part of the upper jaw, the superior labial gland, the 

 anterior part of the parotid gland, within which one of its small 

 twigs anastomoses with a similar twig from the artery supplying 

 the posterior part of this gland, and finally it gives off small 

 vessels to the skin in this region. 



II. A posterior palatine branch (Ramus palatinus recurrens, 

 Schlemm) that goes to the posterior palatine teeth. 



III. Small branches to the anterior palatine teeth. 



IV, Branches to the teeth in the anterior end of the jaw. 

 "V. Branches to the nasal gland. 



The other slightly stouter terminal branch of the facial carotid 

 artery (Art. carotis cerebralis, Schlemm) runs in an irregular arch 

 along the up^jer, inner, and hinder sides of the orbit to the optic 

 foramen, where it anastomoses with the ophthalmic artery. In - 

 this way the blood from the left facial carotid can pass via the 

 ophthalmic artery into the circle of Willis, and thence to the 

 encephalic arteries and also over into the right facial carotid. In 

 its course this artery sends out the following branches : — 



I. Several well-marked twigs to the part of the Harderian 

 gland within the orbit. 



II. Branches to the muscles of the eye (Aa. musculares oculi, 

 Rathke). 



III. Two short ciliary branches (Aa. ciliares posticaj breves, 

 Rathke). 



