38 F, L. LANDACRE 
lateral line fibers. The lateral line fibers join those of the 
lateral line root of X and enter at a somewhat more dorsal 
level, passing into a well defined column in contact with the 
limiting membrane of the lateral wall of the medulla. 
The ganglion petrosum or visceral IX (figs. 1 and 6, G.V.LX), » 
as mentioned above, begins at the point of origin of the ramus 
supratemporalis IX and extends ventrally and caudally to the 
dorsal border of the gill pocket. Its distal end is still in con- 
tact with the epibranchial placode (fig. 7, G.V.IX-+ Pl) and 
cells are evidently being added to the ganglion in the specimen 
plotted. From the distal end of the ganglion extends cau- 
dally a large mass of cells (fig. 1, G.P.JX) closely in contact with 
the ectoderm, which is apparently not yet fully incorporated 
into the ganglion giving it a curious form. ‘The same appear- 
ance is presented by the visceral portion of the VII ganglion 
in a 26 mm. embryo. This mass will probably be incorporated 
with the remaining cells to give the slender spindle-shaped gan- 
glion of the adult. Throughout the whole extent of the petro- 
sal ganglion the visceral motor component of the truncus glosso- 
pharyngeus can be followed, but in the root of the ganglion, 
motor and sensory fibers are so closely fused that they cannot 
be separated. They enter the medulla somewhat more ventral 
than the lateral line root but at the same anterior-posterior level 
(fig. 1, Rt.Vis.IX). 
18. RAMUS SUPRATEMPORALIS IX 
The ramus supratemporalis IX (figs. 1 and 6, R.St.LX) arises 
from the distal end of the lateralis IX ganglion, from which 
point jt runs directly lateral then curves slightly posterior and 
then runs dorsal and slightly anterior. The first twig is given 
off a short distance from its exit from the ganglion and ends on 
a small primordium of a lateral line organ (fig. 1, L.1). A sec- 
ond small twig (not named on figure 1), arises at the same point 
runs slightly more dorsal and comes quite close to the ectoderm 
but does not enter it. The ectoderm is not modified at this 
point and the nature of this twig could not be identified. It re- 
