270 G. E. COGHILL 



passes ventrally of the lateralis ganglion and through the V- 

 shaped cleft of the first myotome, but no fibers can be traced 

 from this region into the brain. 



3. The visceral sensory component. The visceral ganglion of 

 the ninth nerve has enlarged greatly since the last stage, in which 

 it appeared to be receiving cells from the epibranchial placode. 

 It now touches the auditory vesicle (fig. 3, G.Vis.IX). Distally, 

 however, it still reaches to the entoderm, where it has a very 

 indefinite border. Throughout its distal portion it shows two 

 rather distinct portions, the more dorsal of which projects the 

 farther over the entoderm. No nerve trunks are yet to be found 

 arising from this ganglion. It has a root, however, which enters 

 the brain as a relatively strong bundle of fibers on the ventral 

 aspect of the lateral line roots. This relation is shown in figures 

 44 and 45 (R.Vis.IX). The fasciculus solitarius {Fas. Sol.) is 

 seen in figure 42 rostrally of the root. Caudally of the root it 

 appears in figures 45 and 46, where it is larger. The most of 

 the visceral sensory root fibers must, therefore, turn caudad in 

 the fasciculus (fig. 5). 



The visceral ganglion of the vagus still reaches out to the 

 branchial pouches. No peripheral nerves yet arise from it. Its 

 root enters the brain as shown in figures 47 to 49. Figure 47 

 shows ascending vagus fibers just ventrally of the glossopharyn- 

 geal portion of the fasciculus solitarius (X). Figure 49 shows 

 that the fasciculus solitarius {Fas. Sol.) is smaller on the caudal 

 side of the root. It is apparent from this that the visceral sen- 

 sory fibers are directed chiefly cephalad in the fasciculus at this 

 time. The fasciculus solitarius extends only a short distance 

 caudad of the root (fig. 5, R.Vis.X). 



D. THE EARLY SWIMMING STAGE 



1. The lateral line component. In addition to- the lateral Une 

 primordia of the trunk there are now two distinct postauditory 

 primordia, the one innervated by the r. supratemporalis, the 

 other by the lateralis component of the r. auricularis vagi (fig. 4; 

 Paper I, fig. 59) . The lateral line can be traced clearly as far 



