184 THE SPINY DOGFISH— THE SKATE 



(b) The palatine branch of the facial nerve (VII), passing forwards 



from the hyomandibular branch in front of the spiracle and 

 going obliquely across the floor of the orbit to supply the roof 

 of the mouth. 



[In the Skate {Raia) the facial nerve (VII) gives off the following branches : — 



(a) The superior ophthalmic, which is fused with the superior ophthalmic of 



the trigeminal and which supplies the snout {sensory ampulke). 



(b) The inner buccal, which runs under the eye and through the nasal capsule 



to the inner buccal ampulke. 



(c) The outer buccal, which runs under the eye, eicternal to the olfactory capsule, 



and goes to the outer buccal ampullce. 



(d) The palatine, passing downwards in front of the spiracle, and supplying 



the roof of the mouth. It gives off a small prespiracular branch to the 

 front of the spiracle. 



(e) The hyomandibular, passing outwards behind the spiracle and the man- 



dibular muscle, and giving off the following branches : — 



(a) The recurrent facial, running external to the auditory capsule. 

 (/3) The internal mandibular or " chorda tympani," going under the 



spiracle to the inner side of the jaw. 

 (7) The facial proper, supplying the muscles of the hyoid arch. 

 (S) The hyoidean or postspiracular, passing downwards to the muscles 



and ampulke of the hyoid arch. 

 (e) The external mandibular {a branch from the hyoidean), passing 



behind and round the mandibular muscle to the mandibular 



ampulke.] 



(c) The auditory nerve (VIII), arising behind the facial nerve from 



the side of the medulla and passing directly into the auditory 

 capsule, and in its course crossing the glosso-pharyngeal 

 ner%'-e (IX), 



(ix) The glosso-phar5Tigeal nerve (IX), arising from about the middle of the 

 medulla oblongata, and passing back across the floor of the auditory 

 capsule to supply the first gill-cleft, 

 (x) The vagus or pneumogastric nerve (X), arising just behind bhe glosso- 

 pharyngeal nerve, by several smaller roots which fuse together to 

 form a conspicuous nerve. The vagus divides into a branchial nerve, 

 which gives off four branches supplying the second to fifth gill- 

 clefts, and a lateral nerve running along the side of the body and 

 supplying the lateral line. After giving off the branchial branches to 

 the gill-clefts, the branchial nerve passes backwards as the visceral 

 nerve to the heart and stomach and other viscera. Slit open the 

 anterior cardinal sinus to show the branchial branches passing along 

 its inner wall and across the floor. 



(xi) The abducent nerve (VI), a small inconspicuous nerve completely con- 

 cealed by the brain. It can be seen under the posterior rectus muscle, 

 which it supplies ; and it may be traced below the inferior ophthalmic 



