530 H. W. NOERIS AND SALLY P. HUGHES 



5. Lateralis components in the facial rierve of the larva of 



Ichthyophis 



As shown in figure 30 (a projection of the V-VII-VIII ganglia 

 of a larval Ichthyophis), there are two lateral-line ganglia in 

 the complex, an anterior dorsal (gild.) and a posterior ventral 

 (gllv.). From the first the rami ophthalmicus superficialis (os.) 

 and buccalis (buc.) pass anteriorly; from the second there also 

 run two nerves, a larger anterior mentalis externus {mtl.ext.), 

 which supplies the oral series of neuromasts and accompanies 

 the main ramulus mandibularis externus V along the lateral 

 border of the lower jaw, and a posterior mentalis internus {mtl.int.) 

 which supplies the gular series of neuromasts of the lower jaw. 

 The ramus alveolaris VII passes out of the ganglion with the 

 latter nerve. The ramus buccalis, at the level where the ramus 

 maxillaris V divides into lateral and medial divisions, sends off a 

 medial branch {huc.2) which runs anteriorly, closely parallel- 

 ing the course of the combined medial maxillary and palatine 

 branches {pal.l + mx.l). It supplies neuromasts on the tip 

 of the snout (figs. 19, 43). In Siren a strictly comparable branch 

 occurs, a branch of the buccalis {huc.2) which passes ventrally 

 (together with cutaneous fibers of the maxillaris) into the pala- 

 tine-ophthalmic anastomosis, but quickly separates to run to 

 neuromasts on the tip of the snout. 



The structure and relationships of the lateralis ganglia and 

 nerve trunks in a larval caecilian (fig. 43) are in essentials like 

 those in the Urodela. 



THE AUDITORY NERVE 



The fibers of the auditory nerve enter the brain in close asso- 

 ciation with the visceral sensory root of the facialis. Although 

 the otic capsule and the internal ear have the form and arrange- 

 ment of the fully developed ear in the Urodela, it is evident that 

 the auditory ganglion is more or less rudimentary. It consists 

 of an anterior transversely situated mass of cells, constituting 

 apparently a vestibular ganglion, continuous posteriorly with a 

 longitudinal vertical, extremely thin ganglionic mass, a saccular 



