466 LANDACRE AND McLELLAN 
thymus gland. The ramus pharyngeus pursues a similar course 
downward and forward on the mesial surface of the thymus gland 
and is distributed to the roof of the pharynx. The ramus com- 
municans [X ad VII leaves the dorsal surface of the [X ganglion 
at its anterior end and pursues a course forward and downward 
on the mesial surface of the thymus gland which it leaves finally 
and, swinging towards the middle line of the body, joins the hyo- 
mandibular VII at the posterior border of the eye capsule. 
The root of visceral [X can be followed with ease on both the 
8 mm. and 10 mm. larvae back to the point where it becomes 
fused with that of visceral X (figs. 1 and 2, R.JX). At this point 
there is not sufficient difference between the fibers of various roots 
to enable us to follow them through the ganglion with absolute 
certainty. The apparent course is indicated in figures 1 and 2 
and at the point of emergence from the X ganglion to enter the 
brain the arrangement with one exception agrees identically with 
the description of Strong. Strong describes five roots entering 
the brain from the X, but up to the 10 mm. stage only four can 
be found. The fifth of Strong’s nomenclature is a pure motor 
root and is probably in our plot combined with the fourth. 
THE LATERALIS IX GANGLION 
This is a small ganglion situated on the root of the [X nerve 
just posterior to and at the level of the middle of the ear capsule 
(figs. 1, 2, 5 and 9, L.JX). The position is somewhat variable. 
In its early stages it has no connection with the lateralis X gan- 
glion. It does, however, in the later stages become fused more or 
less with either the dorsal lateralis or the ventral lateralis. Its 
relation with the root of IX is constant, always being in contact 
with it. It may lie dorsal, ventral, or posterior to this root, but 
itsone constant relation iswith the IX. The fact that in itsearlier 
stages it is completely detached from X leaves little doubt that, 
while it later becomes fused with X, it is really a lateralis [X gan- 
glion and does not belong morphologically to X. The enormous 
size of the auditory capsule, resulting in crowding the root of the 
IX back till it joins the X, and the large size of the lateralis X 
ganglion account for its later fusion with these ganglia. This 
