CRANIAL NERVES OF SIREN LACERTINA 299 
medial border of Meckel’s cartilage (figs. 8-6). The two nerves 
fuse into one in some cases, in others they merely come into con- 
tact without losing their individuality. Even where a fusion 
occurs there soon results a separation into two branches which 
run along the dorso-medial border of Meckel’s cartilage, supplying 
the overlying mucous membrane and presumably the opercular 
teeth. The larger ventral division of the main alveolaris stem 
(alv.2) passes anteriorly just dorsal to the origin of the intermandi- 
bular muscle on the gonial bone, at the extreme lateral border 
of the mouth just beneath the mucous membrane, and medial to 
the gonial bone and more anteriorly medial to Meckel’s cartilage 
(figs. 8-5). It supplies the mucous membrane of the sides and 
more anteriorly of the floor of the mouth. 
The accounts given of the distribution and relationships of 
the alveolaris in various Urodela differ very widely in detail. 
In Amblystoma (Coghill, 1902) the alveolaris enters a canal in 
the lower jaw, divides within the canal and one. of its branches 
unites with a branch of the mandibularis V. Sometimes it 
gives off a branch before entering the jaw, but in that case the 
branch enters a special canal of its own in the jaw. Apparently 
all of the alveolaris in Amblystoma enters a canal in the jaw. In 
Spelerpes Miss Bowers (’00) finds no branch of the alveolaris 
entering the jaw, but in this she is plainly mistaken, for prepara- 
tions of Spelerpes in the possession of the writer show unmistak- 
ably that the alveolaris divides, one branch entering the jaw and 
fusing with a branch of the mandibularis V, the other branch 
running along the inner border of the jaw as described by Miss 
Bowers. In Amphiuma (Norris ’08) the nerve divides into a 
number of terminal branches, one of which enters a canal in the 
jaw and anastomoses with a branch of the mandibularis V. In 
- Plethodon (Norris ’09) the condition is almost identical with that 
in Spelerpes. In larval Triton (Driiner ’01) the alveolaris gives 
off a large branch before entering the jaw. In the adult Triton 
the chief part of the nerve does not enter the jaw. InSalamandra - 
(Driiner, 1. c.) the alveolaris enters a canal in the jaw and fuses 
with a branch of the mandibularis V. In Cryptobranchus alle- 
ghaniensis and C. japonicus (Driiner ’04) the alveolaris enters a 
