2/2 G. E. COGHILL 



root (fig. 4, R,XI), which in this stage extends caudad to the 

 level of the third myotome (compare Coghill '02, fig. 1, root 

 X4,ci,h,c,d). The latter root is probably largely motor in the 

 early swimming stage, although cells that look like neuroblasts 

 occasionally occur in it. The root of the jugular ganglion enters 

 the descending trigeminal tract, as shown in figure 6. The diffuse 

 nature of the tract in this region is illustrated in figures 66 to 

 70 {Tr.Des.V). 



3. The visceral sensory component. The end of the glosso- 

 pharyngeal ganglion still rests upon the entoderm, but there is 

 now a postbranchial nerve arising from it which extends ventrad 

 behind the pouch and runs a considerable distance rostrad in the 

 primordium of the first branchial bar (fig. 4, G.Vis.IX,g). This 

 is the ramus lingualis. 



No fibers can be traced from this nerve to the skin. Neither 

 do fibers pass from it into the entoderm. Nevertheless it must 

 be primarily visceral sensory, although it may at this time con- 

 tain motor fibers also. The nerve adheres in its course very 

 closely to muscle primordia, just as do the r. mandibularis V, 

 and the r. hyomandibularis VII of this age. 



The root of this nerve still enters the brain in close contact 

 with the ventral surface of the lateral line component (figs. 4 

 63, 64). Figures 62 and 65, respectively, show the condition 

 just rostrally and caudally of the entrance of the root fibers, which 

 join the fasciculus solitarius {Fas. Sol.). 



The projections of the vagus ganglion have not yet completely 

 lost their connection with the entoderm of the first and second 

 branchial pouches, while the caudal portion of the ganglion frays 

 out into loose cells over the branchial region. The first n. 

 branchialis vagi passes some distance into the primordium of the 

 second gill arch behind the corresponding pouch, but it is not as 

 well developed as the r. lingualis of the glossopharyngeus (fig. 

 4, G.Vis.X,h). No other nerves can be found arising from the 

 ganglion at this time. There appear to be no pharyngeal or 

 prebranchial divisions of any of the postauditory branchial nerves 

 in the early swimming stage. 



