Are LANDACRE AND McLELLAN 
THE GENERAL SOMATIC X (JUGULAR) 
The somatic X ganglion (figs. 1, 2, 6, 10, Cu.X.) occupies the 
mesial position in the proximal mass, or first division of the X 
ganglion. It is in the 8 mm. and 10 mm. embryos entirely out- 
side the cavity in which the medulla lies. As the head becomes 
broader and the whole X complex assumes a position more hori- 
zontal, general somatic X comes to lie ventral to the dorsal later- 
alis X and also shifts its position somewhat more proximal so that 
in 235mm. embryo its anterior end is intracranial, the remainder 
of it lying in the jugular foramen. This shifting of position gives 
the ganglion the general position occupied by the jugular ganglion 
in some of the fishes, i.e., intracranial. It extends further for- 
wards than the dorsal lateralis X, but does not reach farther than 
the middle of that ganglion posteriorly. Its ventral border is 
usually in contact with visceral X, while its lateral, and later its 
dorsal border, are in contact with the mesial surface of dorsal 
lateralis X. The cells of this ganglion are smaller than those of 
either lateralis X but not so closely packed as those of visceral 
X. The ganglion is quite large, much larger than the jugular at 
similar stages in Ameiurus or Lepidosteus. 
There is little difficulty in locating this ganglion in Strong’s 
plot. It represents a portion of his ganglion A. It is quite 
distinct in all stages of the embryo up to and including the 10 
mim. stage. The most conspicuous nerve arising from this gan- 
glion is the ramus auricularis, (2) of Strong’s plot. He figures it as 
a pure general cutaneous nerve. It seems to be such in the em- 
bryo, but arises from the X ganglion in both Amblystoma and 
Amphiuma as a mixed nerve containing both general cutaneous 
and lateralis fibers. Its point of origin from the jugular ganglion 
is so close to the dorsal lateralis that there may possibly be later- 
alis fibers in it. Strong’s interpretation of it as a pure general 
somatic nerve seems to hold however for the embryos we have 
studied. 
The ramus auricularis arises from the anterior border of the 
ganglion at about the middle of its dorso-ventral extent and arches 
forward and outward to curve around the posterior border of the 
auditory capsule. A comparison of figures 1 and 2 will show 
