ae H. W. NORRIS 
manner similar to the preceding, to take a position on the 
medial border of the third branchial arch. As described in other 
Urodela the ramus pretrematicus of the third arch arises from the 
truncus intestino-accessorius X. 
8. The truncus intestino-accessorius X 
In the great mass of nerves passing posteriorly from the vagus 
ganglion (fig. 40) the truncus intestino-accessorius is the largest. - 
It occupies a ventro-medial position in the bundle: At the poste- — 
rior edge of the posterior thymus gland (fig. 41) the dispersal of 
these vagal derivatives begins to become noticeable, and a little 
posterior to this the intestino-accessorius begins to curve dorsally. 
At the posterior border of the dorso-laryngeus muscle it occupies 
a position at the ventral border of the scapula and at this point it 
begins to recurve upon itself, passing ventrally and laterally, 
and, at the lateral angle of the esophagus, dividing into three 
divisions (figs. 42-44). At this point where the intestino-acces- 
sorius begins to recurve upon itself there occur, in some specimens, 
numerous ganglion cells, situated on the dorsal border of the nerve 
and evidently belonging to the lateral line constituent. In one 
instance there were about seventy-five of these ganglion cells, 
in another only one ganglion cell was found; in most specimens 
none whatever. These cells are clearly of no especial significance, 
but are merely cells which have wandered out from the dorsal- 
lateral line part of the vagus ganglion. About half-way back 
from the ganglion to the point where the nerve divides there is 
given off from its dorsal border a small motor nerve (dl.2 + trap.) 
which supplies the trapezius muscle and a part of the dorsal por- 
tion of the dorso-laryngeus muscle. In figure 42, for the sake of 
clearness, the origin of this small branch is placed farther poste- 
riorly. The nerve supplying the levator muscle of the fourth 
branchial arch (lab.4) arises in other Urodela from the ramus 
intestino-accessorius, usually far posterior on the latter. In 
Siren it may arise from the third branchial nerve near the gang- 
lion, or from the intestino-accessorius near the point where the 
latter leaves the ganglion. In any case it is an independent nerve 
nearly to the ganglion. Another motor branch to the dorso- 
