NEKVES OF THE DOGFISH 353 



7. The ramus palatinus VII 



From the enlarged proximal portion of the geniculate ganglion 

 there passes out through the wall of the hyomandibular canal 

 ventrolaterally a nerve of visceral sensory composition, that on 

 emerging turns anteroventrally soon dividing into an anterior 

 and a posterior branch (figs. 21, 22, 48, and 51, prt. VII, pal.). 

 The anterior division passes anteriorly, situated between the 

 base of the cranium and the palatoquadrate bar, dorsal to the 

 roof of the mouth. It continues anteriorly in this position, giv- 

 ing off branches to the dorsal oral epithelium: ramus palatinus 

 VII. The posterior branch passes posteriorly at the mesial 

 ventral border of the palatoquadrate bar, giving off branches to 

 the dorsolateral oral membrane, until the level of the anterior 

 wall of the spiracle is reached. Here it turns ventrally and 

 anteriorly and runs along the dorsolateral surface of Meckel's 

 cartilage, farther anteriorly breaking up into small branches 

 supplying the ventrolateral oral surfaces — the so-called chorda 

 tympani. From the geniculate ganglion slightly posterior to 

 the point of origin of the ramus palatinus, there are given off 

 two or three small nerves that supply the pseudobranch and the 

 anterior wall of the spiracle (figs. 21, 22, 48 and 51). These 

 have been termed ramus pretrematicus by various authors. 



8. General reflections upon the facial nerve 



Excluding the lateral-line elements, the facial nerve exhibits 

 the three characteristics of a branchial nerve: ramus pharyngeus 

 (palatinus), ramus pretrematicus (so-called chorda tympani) and 

 ramus posttrematicus (hyomandibularis) . The hitherto so- 

 called rami pretrematici are to be regarded as twigs that belong 

 to the palatinus and pretrematicus proper, but are given off 

 separately. The anastomoses that occur between these so- 

 called pretrematic rami and the ramus pretrematicus proper 

 support the view of their common origin. The rami hyoideus 

 and mandibularis internus may be regarded as the visceral 

 motor and visceral sensory constituents of a ramus posttrema- 

 ticus. Divergent opinions have been expressed as to the homol- 



