532 H. W. NORRIS AND SALLY P. HUGHES 



3) visceral sensory, somatic sensory, and visceral motor rootlets, 

 often in two or more roots, vagus roots proper; 4) motor fibers, 

 forming an accessory group. In the caecilians the first and sec- 

 ond vagus roots correspond to the third urodele group, but the 

 somatic sensory fibers are absent; the third and fourth roots 

 form the accessory element of the vagus. In the frog tadpole 

 Strong ('95) shows four roots of the vagus exclusive of the lateral 

 line element. The anterior of these is visceral sensory and 

 motor; the second is visceral sensory, somatic sensory, and vis- 

 ceral motor; the third is motor with a small visceral sensory 

 contingent; the fourth is exclusively motor. 



In the larva of Ichthyophis a lateral line root of the vagus 

 enters the dorsal part of the medulla. 



The absence of a somatic sensory component from the IX-X 

 complex is noteworthy. 



In Herpele the IX-X roots run out to the mesial wall of the 

 ear capsule and pass back in a groove at the mesial-ventral border 

 of the posterior semicircular canal (fig. 33, IXr., Xr.), thence 

 laterally around the posterior border of the latter and dorsal to 

 the wall of the posterior extension of the sacculus. Close to the 

 emergence from the skull is a small ganglion, usually on the 

 posterior border of the nerve roots, which evidently belongs to 

 the vagus nerve (figs. 32, 44, g.Xr.). The glossopharyngeal 

 and vagal nerve roots in Herpele are so closely joined that it is 

 difficult to distinguish one from the other as they pass out of the 

 skull. When, a thin layer of connective tissue separates them 

 it is possible to trace the fibers of the ninth nerve out past the 

 small ganglion mentioned above and into a ganglion situated 

 dorsal to the sympathetic chain and anterolateral to a second 

 and larger ganglion on the vagus trunk (fig. 44, ggl., g.Xtr.). 

 There is thus seen to be two ganglia upon the vagus, a small 

 ganglion near the exit of the nerve, and a larger elongate one 

 farther laterally dorsal to the sympathetic chain. The first, 

 for want of a more exact term, may be called the root ganglion 

 and the second the trunk ganglion. In some instances the roots 

 of the ninth and tenth nerves are so closely united that the glos- 

 sopharyngeal and vagus trunk gangha are indistinguishably fused 



