588 "Journal of Comparative Neurology and Psychology. 



The trunk of the IX nerve continues down in the branchial 

 arch (figs. 7 to 11) and gives off twigs and single fibers but no 

 large branches. The fibers supply the gill lamellae and whole 

 lining of the posterior half of the first gill sac, forming rich net- 



FiG. 18. The ventral branch of ramus visceralis IX ramifying in the floor of the respiratory tube. 

 Magnification, 60 diameters. The finer fibers could not be drawn. 



works around both internal and external gill openings, meeting 

 and interlacing at these places with the fibers of the VII nerve. 

 The innervation about the external opening of the first gill sac is 

 shown in fig. 19. This is a horizontal section and the fibers 

 approaching from below are those of the IX nerve, those from 



