328 H. W. NORRIS 
This arises, not as in the other Urodela from the ramus intestino- 
accessorius X along with the ramus pretrematicus, but independ- 
ently from the ramus intestino-accessorius near the vagus ganglion 
or directly from the ganglion. 
A fifth branchial nerve is seen in a ramus pretrematicus (X.4, 
prt.) on the inner border of the fourth branchial arch, derived 
from a second pharyngeal branch (s-r.2) of the ramus recurrens 
sensivitus X. As has been noted, this pretrematic ramus is 
double. There is possibly to be seen here in this double condition 
a remnant of a sixth branchial pretrematic ramus. With one 
of these pretrematic nerves on the fourth branchial arch occurs 
an anastomosis from the descending portion of the main trunk of 
the ramus recurrens sensitivus. In Siredon Driiner describes a 
communis anastomosis between the ramus intestino-recurrens X 
and the remnant of the fifth branchial nerve. In the Urodela in 
general, as far as investigated, the fifth branchial pretrematic 
arises with the fourth from the ramus intestino-accessorius. 
From the ramus intestino-accessorius X of Siren, about opposite 
the fourth branchial arch, a large pharyngeal branch (ph.i-a.),_ 
arises, which possibly represents combined pharyngeal rami of the 
fourth and fifth branchial nerves. As noted, Driiner interprets 
the ramus recurrens sensitivus X, and, in part at least, correctly, 
as a representative of a possible fifth branchial nerve. Its posi- 
tion and relations justify such an assumption, but to the writer, 
as previously stated, it seems more reasonable to regard it as the 
communis portion of the ramus intestino-recurrens. In so far 
as the latter represents posterior branchial nerves the ramus 
recurrens sensitivus is also to be included in the same category. 
11. The rami laterales dorsalis et medius 
These two nerves have the same general course and distribu- 
tion as in the Urodela in general, supplying the dorsal and medial 
series of neuromasts of the trunk. The statement of Driiner that 
all three main lateral line nerves leave the ganglion in a common 
trunk has not been verified. 
