18 F. L. LANDACRE 
small ganglion lying on the root of the vagus intracranially. 
At this time its ganglionic cells cannot be distinguished from 
embryonic sheath cells. 
The lateralis X 
The lateralis X is the best defined ganglion of the vagus group. 
It is an elongated cylindrical mass of cells with its anterior end 
reaching the posterior end of the first branchial ganglion of the 
vagus and its posterior end reaching posterior to the caudal end 
of the visceral X. It is situated laterally in the body at the level 
of the notochord and lies between the skin and the branchial 
ganglia of the vagus. I can detect only two fibrillated nerves 
arising from it at this time. The chief nerve (ramus lateralis 
vagi), arises from the posterior end of the ganglion and runs 
posteriorly as usual in teleosts. The second nerve is the ramus 
supra-temporalis vagi which arises from the anterior end of the 
lateralis X ganglion and passes directly lateral and slightly forward 
to a lateral line organ apparently the third organ of the body 
lateral line. 
The root of this ganglion does not enter with the vagus roots 
but pursues a course diagonally forward and upward to the region 
of the root of the glossopharyngus with which at this stage, it 
enters the medulla. In older embryos the fibrillated root of the 
lateralis X passes beyond the visceral root of the IX and enters 
the medulla anterior to that root. 
The branchial ganglia of the vagus 
The first branchial ganglion of the vagus (figs. 1 and 11) is a 
visceral ganglion composed of cells derived from the neural crest 
(general visceral) and of cells derived from the placode of the 
second true gill (special visceral or gustatory). In shape it 
resembles the glossopharyngeal but has a position more nearly 
vertical in the body. The ventral end is the larger and it 
curves dorsally and at this stage comes into contact at its dorsal 
and posterior border with the remaining portion of the general 
visceral mass of the X. It is convex on its anterior face. The 
