NERVES OF THE DOGFISH 359 



fering from the pharyngeal and pretrematic in possessing visceral 

 motor fibers in its main portion. 



Within its canal in the ear capsule the ninth nerve emerges 

 from the posterior end of the visceral ganglion in two portions, a 

 smaller lateral visceral sensory part, and a large mesial portion 

 of sensory and motor composition (figs. 24, 48, 51, and 52). On 

 emerging from the canal in the ear capsule, the smaller portion 

 divides into two chief branches at the ventromesial border of the 

 thymus gland. The mesial one of these divisions turns anteriorly 

 along the roof of the pharynx and mouth dorsally : ramus pharyn- 

 geus IX (figs. 48, 51 and 52, ph. IX). The lateral branch of the 

 lateral sensory division of the glossopharyngeus turns antero- 

 ventrally from its point of separation from the mesial branch 

 and runs along the anterior wall of the first gill cleft — ramus 

 pretrematicus IX (figs. 48 and 51, prt. IX). 



After giving off the rr. pharyngeus and pretrematicus, the 

 remaining fibers of the ninth nerve constitute a large nerve lying 

 dorsal to the mesial end of the first epibranchial cartilage. 

 Along the anterolateral face of this cartilage it runs ventrally, 

 curving at first posteriorly and then ventrally as it shifts over 

 to the first ceratobranchial cartilage. It runs along the dorso- 

 lateral border, later along the ventrolateral border of this car- 

 tilage. Shifting to the mesial border, it runs to the extreme 

 anterior tip of the cartilage and farther anteriorly at the dorso- 

 lateral border of the coracobranchialis muscle, beyond the ante- 

 rior end of which it runs at the dorsomesial border of the poste- 

 rior horn of the basihyal. . Farther anteriorly it passes along the 

 dorsal border of the lateral portion of the main part of the basi- 

 hyal cartilage, supplying the mucous membrane of the floor of 

 the pharynx and mouth. Besides the chief portion of the ramus 

 posttrematicus there are some secondary parts given off as 

 small visceral sensory branches (fig. 48, pst. IXa) that run 

 more directly anteroventrally across the anterolateral face of the 

 epibranchial cartilage, thence along the ceratobranchial bar a 

 little dorsal to the main ramus. The general course of the 

 ramus posttrematicus IX is thus seen to be along the mucous 

 membrane of the posterior wall of the first gill-cleft. 



