CEANIAL NERVES OF CAECILIANS 527 



Just before the lateral branch of the ramus palatinus {Pal.2) 

 unites with the medial division of the ramus maxillaris (mx.l), 

 a small ganglion , (figs. 29, 44, gpal.) occurs on the former. 

 This ganglion is so much flattened horizontally that in a cross- 

 section of the head it is detected with difficulty. From the 

 ganglion small nerves proceed, one anterolaterally and the other 

 posterolaterally. In Dermophis and the larva of Ichthyophis a 

 palatine ganglion occurs in essentially the same relationships as 

 in Herpele. Apparently it is absent in Geotrypetes. 



In Amblystoma, according to Coghill, there is a ganglion on 

 the ramus palatinus at the junction of its lateral division with 

 the lateral division of the trigeminal element in the palatine- 

 trigeminal anastomosis. Norris found in Amphiuma scattered 

 ganglion cells just before the anastomosis is reached. 



3. The truncus hyomandihularis VII 



This trunk passes directly posteriorly from the geniculate 

 ganglion in a space between the anterior ventral edge of the 

 auditory capsule and the suspensorium (fig. 29, VII). When 

 the stapes is reached the nerve takes a position on the dorsal 

 border of the latter, at the ventrolateral border of the ear cap- 

 sule. The two sympathetic nerves from the Gasserian and genicu- 

 late ganglia unite into a single trunk and the latter joins the 

 ramus hyomandibularis, running first along its dorsal and then 

 its medial border, soon becoming sharply distinct from the 

 ramus hyomandibularis. The first branch given off from the 

 hyomandibular ramus is a motor nerve to the anterior part of 

 the depressor mandibulae muscle (fig. 44, dma.) almost im- 

 mediately followed by a visceral sensory nerve {ah.) which 

 curves ventrally around the lateral border of the stapes, along 

 the medial border of the depressor mandibulae muscle, and, 

 reaching the lower jaw, enters a canal in the gonial bone, in which, 

 as the ramus alveolaris VII, it runs anteriorly to its junction 

 with the ramulus alveolaris V, as previously described. A short 

 distance posterior to the ramus alveolaris a second branch is 

 given off to the depressor mandibulae muscle, innervating the 



