THE NERVOUS SYSTEM OF AMPHIBIA 271 



caudad as the seventeenth myotome, almost the full extent of 

 the primordia. Fibers reach the primordium of the inferior Hne, 

 also. The small lateral hne ganglion which is associated with 

 the r. auricularis vagi still stands out distinctly. The root 

 fibers from the gangha on the vagus pass to the brain on the 

 dorsal surface of the root of the ninth nerve. The root fibers 

 have extended their tracts as indicated in figure 6 {L.L.IX,X 

 Asc.,Des.). The relation of the root fibers to the tracts is shown 

 in figures 62 to 65. The roots here are very compact bundles 

 of fibers. There is no apparent interchange of fibers between 

 the roots from the different ganglia. The dorsal tract seems to 

 represent the vagus ganglion and the ventral tract the glosso- 

 pharyngeal ganglion. The ventral tract runs rostrad in very 

 close relation to the fasciculus sohtarius and at the level of the 

 middle of the auditory vesicle takes a position ventrally of the 

 lateral line tracts of the facial nerve (fig. 61, L.L.IX,XJ)). 



2. The general cutaneous component. The jugular ganghon 

 holds about the same position relative to the other ganglia as in 

 the earUer stages. Only in favorable preparations can it be dis- 

 tinguished from the visceral ganglion, over which it lies in the 

 form of a rather tliin cap. It gives rise to the r. auricularis vagi, 

 which is still a very short nerve. The exact distribution of the 

 fibers can not be made out. General cutaneous fibers join also 

 the projections of the visceral ganglion which reach out to the 

 second and third branchial pouches. It has been impossible to 

 demonstrate fibers from the jugular ganghon to the external gills, 

 to the skin around the base of the gills or to the ventral surfaces 

 of this part of the head. The cutaneous innervation, so far as 

 the ganglionic system is concerned, is in a much lower state of 

 development in the post auditory region than it is in the pre- 

 auditory. 



The root of the jugular ganghon now reaches the brain, pass- 

 ing across the dorsal surface of the visceral root from the rostral 

 to the caudal side (fig. 4, R.GJug.). It enters the brain at a 

 slightly more ventral level than does the visceral root, as shown 

 in figures 67 to 69 {R.GJug., fig. 69). This root is continuous 

 from the ganghon to the brain surface with the spinal accessory 



