50 F, L. LANDACRE 
34. THIRD TRUNCUS,BRANCHIALIS X 
The third branchialis ramus repeats the pattern of the sec- 
ond, having a ramus pharyngeus (fig. 1, R.Ph.X;) and ramus 
pretrematicus (figs. 1, 11, R.Pr.X;) with the same relation to 
the epibranchial ganglion. The posttrematic ramus (figs. 1, 12, 
R.PoX;) seems to lack sensory fibers; at least none could be 
detected. The terminal ramus of the third posttrematic nerve 
curves forward to end on the primordium of the branchial mus- 
culature, and, in fact, the whole ramus forms a gentle curve 
cephalad. The rami of the fourth branchial nerve are small, 
particularly the ramus pharyngeus and the ramus pretrematicus. 
35. FOURTH TRUNCUS BRANCHIALIS X 
The first division of the fourth branchial nerve arises as two 
minute twigs in the position occupied by the ramus pharyngeus 
and ramus pretrematicus on the more anterior branchial gan- 
glia. They (fig. 1, R.Ph.X,and R.Pr.X,) are identified as these 
nerves although their minute size prevents their being followed 
to their terminations. The ramus posttrematicus (figs. 1, 13, 
R.PoX:) is much easier to follow and pursues a course behind 
the last gill slit ventrally, then curves slightly forward to pass 
to the heart, where it can be identified last near the wall of the 
pericardium. It is identified provisionally as the ramus Car- 
diacus X. 
36. THE GANGLION VISCERALE X; 
The fifth branchial ganglion (figs. 1, 12, 13, G.V.X;) extends 
caudad from the fourth as a large mass of cells fully as large as 
any of the preceding branchial ganglia. At its posterior end 
it is fused with an indertation of the ectoderm, as are the more 
anterior branchial ganglia at their attachment to the placodes 
(fig. 1, G.P.X;). The attachment is small and there is no cor- 
responding pharyngeal evagination. The large bundle of fibers 
that has accompanied all the remaining branchial ganglia lying 
on their ventral or mesial surfaces, disappears in this ganglion. 
