140 STRONG. [Vol. X. 



the R. auricularis vagi of higher forms, this is also correct. 

 But this branch is not a part of the lateral line system. 



Along this portion of the main trunk, the ganglion cells, 

 which are nearly or entirely absent from that part of the trunk 

 lying outside the apex of the auditory capsule {i.e., separated 

 by the tip of the capsule from the inner part in transverse 

 sections), increase in number, forming the second ganglion 

 mentioned. This ganglion, however, is confined to the outer 

 part of the trunk, and there is a large bundle of non-ganglion- 

 ated fibres running along just inside it and close to the auditory 

 capsule. 



The third branch (j) separates from this outer ganglionated 

 part of the trunk (931-949) and proceeds ventrad, sloping 

 mesad and caudad (PI. XI, Fig. 40). It contains ganglion cells 

 along its course, and finally, on a level with the oesophagus, 

 contains a considerable group of ganglion cells, meriting the 

 name ganglion. The fibres of this branch are principally fine 

 and many of them impregnate in Golgi preparations, as is 

 shown in the figure. Where the branch separates from the main 

 trunk, a small twig is given off from its dorsal side, as shown 

 in the figure, which apparently contains mixed fibres, some of 

 which innervate a blood vessel proceeding dorsad here (cuta- 

 neous artery }) and some of which possibly innervate a muscle 

 just outside the auditory capsule. 



Three principal branches proceed usually from the group of 

 ganglion cells. They proceed caudad, some giving off branches 

 to the oesophagus. Others were not traced completely, but 

 they are probably pulmonary or gastric branches. One branch 

 soon curves mesad and, proceeding cephalad, reaches the heart, 

 which it innervates. It is ganglionated on the auriculo-ventric- 

 ular septum (Bidder's ganglion). From this ganglion the 

 nerve passes down along the ventricle, giving off innumerable 

 branches, which penetrate to every portion. The general 

 appearance of this plexus is indicated in PI. IX, Fig. 14. As this 

 shows, there are also numerous fibres innervating the walls of 

 the auricles. 



The third branch is the R. visceralis. 



In addition to these branches there are other minute twigs 



