CRANIAL NERVES OF SIREN LACERTINA 319 
the ramus supratemporalis X. Passing posteriorly and dorsally, 
it anastomoses with another vagus branch of lateralis and general 
cutaneous fibers which has arisen almost directly dorsal to the 
exit of the ramus supratemporalis. The two nerves combined 
innervate the neuromasts of the occipital series, receiving the 
anastomosis from the facial dorsal lateral line ganglion. The 
general cutaneous fibers of the auricularis supply the skin in the 
occipital region. 
6. The second branchial nerve 
The nerves taking their origin from the posterior part of the 
vagus ganglion, as Driiner has observed, are bound into a com- 
pact bundle which passes posteriorly as such, before any important 
branches are given off, as far as the anterior border of the anterior 
thymus gland. Examination of cross-sections of this nerve shows 
that the characteristic vagus rami, although in close juxtaposi- 
tion, are distinct throughout (figs. 40, 41). In figures 42 to.44 
these nerves are represented as somewhat displaced vertically 
in order to show the component parts. The writer is unable to 
confirm Driiners’ statement that all three lateral line nerves are 
bound into a truncus lateralis, nor that the third branchial nerve 
is bound into a single stem with the rudiments of the following 
branchial nerves. These nerves are all distinct from each other. 
The second branchial nerve (X.1) leaves the postero-lateral 
border of the vagus ganglion, and soon divides into a dorsal and 
a ventral division, the latter being the ramus pharyngeus. The 
dorsal division passes postero-dorsally, to the extreme dorsal tip 
of the first branchial arch. There it divides, or has already 
divided, into three main divisions: (1) A branch of motor, general 
cutaneous and communis composition (figs. 42, 44, br.1,X.1) 
curves over the top of ceratobranchial 1 and descends on its 
lateral border to the first gill and the levator (l/br.1) and depressor 
(dbr.1) muscles of the same. (2) A little posterior to the preceding 
a second branch, of motor and communis fibers, curves over the 
top of ceratobranchial 2 and descends along its lateral border as 
the ramus posttrematicus (X.1/,pst.). It gives off a motor branch 
to the depressor muscle of the second gill (dbr.2)._ Thence pass- 
