106 ELEMENTARY BIOLOGY. [CHAP. 



y. The ophthalmic or orbito-nasal ; its distribu- 

 tion may now be studied by turning the animal 

 over and examining from the dorsal aspect. 

 Remove the nasal and sphenethmoid bones 

 to its level; and note its branches to the 

 antero-dorsal integument of the head. 



e. The ^th or facial ; intimately connected with 

 the Gasserian ganglion and the trigeminal. Ex- 

 amine it, from the ventral aspect, on that side 

 at which the eye remains. 



a. Its root ; arising, side by side with that of the 

 5th, from the side wall of the medulla ; the 

 two entering the Gasserian ganglion. 



y8. Its anterior branch (palatine nerve) ; leaving 

 the Gasserian ganglion immediately external 

 to the ophthalmic branch of the 5th, and 

 passing forwards, perforating the vomer, to be 

 distributed to the mucous membrane of the 

 roof of the mouth. 



y. The maxillo-palatine commissure ; connecting 

 the palatine and maxillary nerves; on a level 

 with the front end of the eye-ball. 



S. The posterior branch of the 7th ; leaving the 

 outer side of the Gasserian ganglion, im- 

 mediately behind the maxillo-mandibular 

 nerve, and passing outwards and backwards 

 dorsal to the columella auris (beneath it as 

 here seen). Its distribution may best be 

 studied later. 



/ The ()t/i and io//i (post-auditory nerves)-, arising 

 close together from the medulla posteriorly to 



