I50 THE SALAMANDER 



(iii) The R. posterior (n.S.Tp.) gives twigs to the ampulla of the 

 posterior semicircular canal, to the lagena, and to the macula acustica 

 neglecta. 



The R. medianus and its corresponding foramen were first de- 

 scribed for Salamandra by Okajima in 1910, and its existence 

 was confirmed in other Urodeles and in Anura by Miyawaki 

 (1927-9). 



IX and X. NN. Glossopharyngeus and Vagus. 



The roots and ganglia of these two nerves are very closely asso- 

 ciated in the adult Salamander, although — according to Hoffmann 

 — they are distinct in the larva. It is therefore convenient to regard 

 them as forming a complex arising laterally from the sides of the 

 medulla oblongata by three roots, which unite and pass out of the 

 cranial cavity through t\\e, foramen post-oticum (for. metoticum, Stadt- 

 miiller), immediately posterior to the ear-capsule. The composite 

 nerve then swells into a large glossopharyngeus-vagus ganglion which 

 is thus situated outside the skull, in the angle between the ear- 

 capsule and the occipital segment, and at about the level of the 

 dorsal surface of the former. To expose it the MM. depressor 

 mandibulae, cephalo-dorso-subpharyngeus, cucullaris, and inter- 

 transversarius capitis superior must be removed, or turned back. 



IX. N. Glossopharyngeus (n.9) (mixed communis, visceral motor, 

 and a few general cutaneous fibres). The glossopharyngeal nerve 

 separates from the anterior portion of the ganglion and passes 

 lateralwards between the MM. intertransversarius capitis superior 

 and inferior, and then turns ventrad, lateral to the M. opercularis 

 and mesial to the M. cucullaris. As it proceeds it gives off three 

 branches. 



(i) R. communicans ad /^//(seep. 148) separates at about the level 

 of the operculum and passes anteriorly round the otic capsule to join 

 the facial nerve as described above. This branch probably carries 

 only communis fibres from the glossopharyngeus and derives a 

 general cutaneous component from the vagus. 



{^\)R.pre-trematicus{n.^rX.<^ (communis). This branch is given 

 off very soon after the former, and at first passes anteriorly at right 

 angles to the main nerve, but just posterior to the R. jugularis VII 

 it turns ventrad and runs parallel with the internal carotid artery, and 

 anterior to it. The R. pharyngeus (n.phar.) which, arising at the 

 point where it turns ventrad, passes mesially, just anterior to the 

 systemic arch, and is distributed to the mucous epithelium of the 

 pharynx roof. Driiner describes ganglion cells associated with this 



