THE NERVOUS SYSTEM OF AMPHIBIA 269 



enlarged greatly and stretches along the root till it comes into 

 close relation with the lateral line root of the vagus (fig. 3). 

 There is, then, a considerable advance made towards the con- 

 soUdation of all the postauditory lateral line ganglia into a com- 

 mon mass (compare Goghill, '02, figs. 1 and 2). The ganglionic 

 projection, however, which reaches out on the r. auricularis vagi 

 now amounts practically to a distinct ganglion with its own root 

 connection with the main lateral line root of the vagus. In the 

 terminal portion of this smaller ganglion fibers connect with the 

 primordium, but this nerve does not seem to be quite as well 

 developed as the r. supratemporaHs. It is a question whether 

 these two nerves innervate a common primordium (Paper I, 

 fig. 58) or whether there may not be two primordia here sepa- 

 rated by an ectodermal thickening to which the jugular ganglion 

 connects. 



The primorida of the trunk now apj)ear in two distinct patches 

 (Paper I, fig. 58, LL.). One of these lies opposite the tliird and 

 fourth myotomes and the other opposite the seventh to the tenth 

 myotomes. To both of these the main lateral line ganglion of 

 the vagus sends nerves, which separate from each other a short 

 distance from the ganglion. 



Figures 42 to 46 rej)resent five successive serial section which 

 show the lateral line roots entering the brain. There are still 

 two divisions of the roots, a dorsal and ventral, marked, respec- 

 tively, a and h. Each division forms an ascending and a de- 

 scending tract, the longitudinal extent of which is shown in 

 figure 5. 



2. The general cutaneous component. The jugular ganghon still 

 lies on the lateral aspect of the proximal portion of the lateral 

 line ganglion of the vagus as an ill-defined group of cells. It 

 reaches the skin as a ganglion rather than as a nerve, in close 

 relation with the small lateral line ganglion already mentioned. 

 Its point of contact with the skin seems to be between the lateral 

 line primordium innervated by the latter ganglion and that inner- 

 vated by the r. supratemporaHs. It projects also caudad in 

 loose relation with the visceral ganglion, but its relations in this 

 region are ver}' indefinite. A root-like projection of the ganglion 



