42 F, L. LANDACRE 
some of the posterior roots on the opposite side from that 
plotted, are made up exclusively of the ventrally directed roots. 
These roots are identified provisionally, for reasons given above, 
the dorsal as visceral sensory, and the ventral as visceral motor. 
23. THE JUGULAR XTH GANGLION 
The mass of cells identified as the jugular or general cutaneous 
ganglion of X (figs. 1 and 7, G.J.X.) is situated in the proximal 
portion of the X complex. It les lateral to the proximal at- 
tenuated fibrous root and extends from the level of the anterior 
end of the lateralis ganglion on branchial X,, to the middle of 
the lateralis ganglion on X,. It lies dorsal to both these ganglia 
where it comes into contact with them and, except for the fibrous 
bundle running between X, and X,, it forms the ventral bound- 
ary of the Xth complex in this region. This ganglion is com- 
posed of small cells and is apparently in a very immature con- 
dition, as is the same ganglion in Amelurus and Lepidosteus 
(Landacre, ’10 and 712) in approximately the same stage of 
development. No root fibers from this ganglion could be 
identified. 
The mass of cells described above as the jugular ganglion is 
found in a 20 mm. embryo, but is better defined in a 25 mm. 
embryo, where it is well isolated from the ganglia lateralis Xy 
and X, with which it is in contact on its posterior and ventral 
surface. In a 30 mm. embryo this mass of cells is not isolated 
but seems to be fused with lateralis X;. If this interpretation is 
correct, it has migrated, between the 25 mm. stage and the 30 
mm. stage, from a position mesial to the somatic muscle pri- 
mordium to a position lateral to this primordium. This is 
equivalent to a migration from an intracranial to an extra- 
cranial position. 
24, RAMUS AURICULARIS 
The ramus auricularis (figs. 1, 9, 10 and 11, R.Aur.) or ramus 
cutaneous dorsalis vagi has not been identified with certainty. 
There are certainly no well defined nerves of this character 
arising from the dorsal and proximal portion of the Xth gan- 
