THE EPIBRANCHIAL GANGLIA OF LEPIDOSTEUS vl! 
to the ventro-lateral wall of the medulla at a point opposite the 
posterior end of the mesencephalic roof. 
There are two well defined fibrillated nerves arising from this 
ganglion at this time, a supra-orbital trunk (ophthalmicus super- 
ficialis trigeminus), and an infra-orbital trunk (truncus infra- 
orbitalis), which splits up into the maxillary and mandibular 
trunks. 
The supra-orbital trunk (fig. 1) arises from the dorsal surface 
of the posterior end of the ganglion and runs upward and slightly 
forward and becomes so attenuated that it cannot be followed as 
far forward as the posterior border of the optic vesicle. There 
is consequently no connection between supra-orbital V and the 
profundus, such as we see later when these two nerve trunks come 
to lie closer together. 
The infra-orbital trunk is much larger and longer. It arises 
from the extreme anterior and ventral end of the ganglion. It is 
separated from the point of origin of the supra-orbital trunk by 
the whole length of the ganglion. This condition is of course 
temporary, since the Gasserian ganglion becomes shorter as it 
becomes older, and the two points of origin are brought closer 
together. Near its point of origin the infra-orbital trunk divides 
into two branches, a dorsal, the ramus maxillaris V (figs. 4 and 5) 
and a ventral, the ramus mandibularis V. The ramus maxil- 
laris pursues a course forward under the optic vesicle at the level 
of its point of origin and can be followed to the anterior border 
of the vesicle. The ramus mandibularis V runs directly ventral 
into the mandible. All the nerves arising fromthe Gasserian 
ganglion, owing to their freedom from contact with other nerves 
and ganglia, are at this time pure general somatic nerves. 
The VII ganglion is composed, as usual among Ichthyopsida, 
of three more or less distinct masses; a visceral ganglion, the genic- 
ulate, and two lateralis ganglia, the dorso-lateral and ventro- 
lateral. There is more or less fusion between these ganglionic 
masses as well as with the auditory ganglion at various stages of 
their growth and migration into the adult condition; so that it 
will be easier to describe them in the order of their simplicity. 
