GANGLIA OF RANA 475 
BRANCHIALIS X, OR FIRST VISCERALIS X 
This ganglion (figs. 1, 2, 4, 8, G.V.X+) stands in sharp contrast 
to the remaining portion of X both in its shape and in its position 
in the body. It resembles both in shape and position the glos- 
sopharyngeal ganglion. Its long axis is parallel to the long axis 
of the body. It lies under the auditory capsule like the [X and 
not behind it like the remainder of the X. Its general shape 
is that of an elongated S-shaped column of cells, free at its ante- 
rior border but attached at its posterior border to visceralis X2. 
This attachment occurs at the middle or upper third of the ante- 
rior surface of the visceralis X. The anterior end of this ganglion 
lies under the posterior end of the auditory vesicle. From its ante- 
rior end, where a branchial nerve arises, it gradually increases 
in size until it fuses at its posterior end with the visceral X2. 
The position of this ganglion in Strong’s plot is represented 
apparently by ganglion B®. It is from this ganglion that the 
branchial nerves emerge in his plot and Strong’s ganglion C is, 
undoubtedly the glossopharyngeal. The only question in doubt 
is whether branchial X also corresponds to a part of B’. This 
seems improbable since B! is the only ganglion left on Strong’s 
plot that could represent the visceral X2. The extent to which 
the IX + X complex is elongated by the posterior extension of 
the auditory capsule makes it difficult to follow the shifting of 
the ganglia, since there is a stage between the time when the 
ganglia are distinct, as in our plots, and the time when fibril- 
lated paths can be followed, in which it is very difficult to deter- 
mine ganglionic boundaries and still more difficult to separate 
components among fibers. 
An interesting question arises here as to the homology of 
the branchial ganglia in the frog with the branchial ganglia of 
Menidia, Lepidosteus and Ameiurus. In these types there are 
four more or less distinct branchial ganglia in the vagal complex. 
In Lepidosteus, which at a similar stage of development most 
closely resembles the 8 mm. stage of the frog, only one branchial 
nerve, that for the second true gill, arises from the first branchial 
X ganglion. The remaining three arise from the ventral border 
