•254 THE DOG-FISH 



ii. The palatine nerve is a slender nerve which runs 

 forwards and outwards across the floor of the 

 orbit, immediately behind the main stem of 

 the fifth nerve : it then turns forwards be- 

 neath this nerve and runs along the upper jaw, 

 sending branches to the roof of the mouth. 



iii. The hyoidean or post-spiraeular nerve is a 

 much stouter nerve, which runs straight out- 

 wards along the posterior wall of the orbit 

 towards the spiracle. Continuing its course 

 outwards and backwards, in close contact with 

 the anterior wall of the auditory capsule, it 

 passes along the posterior border of the 

 spiracle, where it lies just beneath the skin, 

 and then runs downwards and backwards 

 along the anterior border of the hyoidean 

 arch, giving branches to the muscles of these 

 parts. 



Close to its origin it gives off a number of 

 small pre-spiracular branches to the anterior 

 wall of the spiracle and to the pseudobranch. 



8. The eighth or auditory nerve, immediately after its 



origin, enters the auditory capsule through a hole in 

 its inner wall, and divides into branches supplying 

 the several parts of the internal ear. 



Slice away the auditory ^ capsule down to the level of the 

 root of the auditory nerve, and trace the nerve into it. 



9. The ninth or glosso-pharyngeal is a slender nerve which 



arises from the side of the meduUa, about an eighth 

 of an inch behind the auditory nerve and nearer the 

 ventral surface. It at once enters a foramen on the 

 inner side of the auditory capsule, and passing hori- 

 zontally outwards and backwards along a canal in 

 the floor of the capsule, emerges at its posterior 

 and outer angle, opposite the upper end of the first 

 branchial cleft, where it divides into two branches. 



