GANGLIA AND NERVES OF SQUALUS 30 
fibers from the lateral line ganglion forming the ramus hyo- 
mandibularis that the two components are indistinguishable. 
Consequently the ramus hyomandibularis willbe described sepa- 
rately, since it contains not only visceral sensory fibers from 
the geniculate but lateral line fibers and motor fibers as well. 
15. THE VENTRAL LATERALIS VII GANGLION 
The ganglion identified as ventral lateralis VII (figs. 1 and 
5, G.L.VII V.) occupies the position with reference to the 
geniculate and auditory usually held in the embryos of fishes 
and amphibians (Landacre, ’14) but is surprisingly large in pro- 
portion to the single lateral line primordium innervated by the 
r. hyomandibularis into which all the fibers from this ganglion 
pass. This disproportion may be explained on the basis that, 
while the r. hyomandibularis innervates in the adult at least 
five lateral line organs in the hyomandibular line, only one has 
appeared at this stage. The ventral lateralis VII is approxi- 
mately as large as the geniculate and rather closely fused with 
it, although, as stated in discussing the geniculate, it can at all 
points in the contact be distinguished from it except in the 
r. hyomandibularis, and further the root of the lateral line 
ganglion can be traced into the brain where it enters with that 
of the dorsal lateralis VII. The ventral lateralis ganglion is 
crescent-shaped with the convexity on the ventral side and no 
pure lateral line rami leave it at this time so that the evidence 
for its identity except as presented above is not so definite as 
for the other members of the acustico-facial complex of ganglia. 
16. TRUNCUS HYOMANDIBULARIS 
The truncus hyomandibularis (fig. 1, R.Hyo.VII) is a mixed 
nerve quite compact in structure and easy to follow but some- 
what difficult to analyze. It arises from the posterior fused 
ends of the geniculate and ventral lateralis VII. It pursues a 
course slightly ventro-caudad to a point where it gives off a 
motor twig (fig. 1, Mo.1) to the primordium of the hyoid muscu- 
lature, then turns directly ventral. I+ gives off next three twigs 
THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 27, NO. 1 
