CEANIAL NERVES OF CAECILIANS 531 



ganglion (fig. 28, gacs.). None of the ganglionic cell mass enters 

 the ear capsule, in which respect there is a marked divergence 

 from the condition in the urodeles. The anterior part of the 

 ganglion extends from the brain wall postero-laterally out to the 

 medial wall of the ear capsule. The lateral-line and visceral- 

 sensory components of the facialis run along in and through the 

 anterior border of this vestibular ganglionic material. The 

 nerve which supplies the sense organs of the utriculus and the 

 anterior and horizontal ampullae is given off from the lateral 

 end of this anterior ganglion. From the medial, brain end of 

 the anterior ganglionic mass the remainder of the acoustic gan- 

 glion extends posteriorly as a thin vertical plate of cells, somewhat 

 crescentric in cross-section. From this part of the ganglion are 

 given off five nerves, four ventral ones to the sacculus and one 

 dorsal to the macula neglecta, to the ampulla of the posterior 

 canal, and to a sense-organ in the posterior part of the utriculus 

 which seems to be peculiar to caecilians. 



THE GLOSSOPHARYNGEAL AND VAGUS NERVES 



1. The roots and ganglia of the IX-X complex 



As in other Amphibia, the ninth and tenth nerves are so 

 closely associated that it is difficult to distinguish their proximal 

 portions from each other. In Herpele the two nerves' arise from 

 the brain by five roots or groups of rootlets. Four of these, which 

 represent the vagus, unite into a single one, ventral to which 

 runs a smaller or glossopharyngeal root. In Geotrypetes the 

 exact composition of these roots was determined with precision. 

 The glossopharyngeal root arises, as in other Amphibia, by two 

 rootlets, visceral sensory fibers that enter the fasciculus com- 

 munis, and visceral motor. The first and second vagus roots 

 contain both visceral sensory and visceral motor elements; the 

 third and fourth roots are exclusively motor. Comparison of 

 this condition with that in other amphibians shows that in the 

 Urodela in general there are four groups of rootlets in the IX-X 

 complex: 1) lateral-line root fibers (absent in adult caecilians); 

 2) visceral sensory and motor root fibers of the glossopharyngeus; 



