No. 3-] LATERAL LINE OF AMIA. 513 
important part in innervating the surface sense-organs, or ter- 
minal buds. Its ophthalmic and superior maxillary branches are 
largely devoted to this purpose. They supply no muscles, and 
numerous branches can be traced in sections from each of them 
directly to the surface organs which they supply. The inferior 
maxillary is partly sensory and partly motor, several important 
branches of it being distributed entirely to the surface sense- 
organs and other non-muscular tissues. 
The ophthalmicus profundus is also entirely sensory. A 
small branch pierces the choroid coat of the eye, accompanied 
by a branch of the external carotoid artery, while the rest of 
the nerve fuses completely with the ophthalmic division of the 
trigeminal, so that its special distribution cannot be determined. 
In one set of sections only of all those examined did there 
seem to be a separation of these two nerves on the top of the 
snout, the ophthalmicus profundus being lost in the general 
tissues above the nasal sacks, and doubtless taking part there, 
along with the trigeminal, in the innervation of the surface 
organs. 
The facial is the first one of the cranial nerves that takes any 
part in supplying the regular organs of the lateral canals, and 
it has a large and important part not only in their innervation, 
but also in that of the different lines of pit organs. Four of its 
branches, the ophthalmicus superfacialis, buccalis, oticus, and 
mandibularis externus, are entirely devoted to this purpose. 
The R. ophthalmicus superfacialis facialis supplies all the 
organs of the supra-orbital canal, a separate branch being sent 
from the main nerve to each group of organs. This branch 
pierces the bony canal of the line immediately below the cen- 
tral organ of the group, and after entering the canal sends a 
branch to each organ. This is the method of innervation in 
all the canals. Posterior to all the branches sent to the different 
groups of supra-orbital organs, still another branch —the most 
posterior one of the R. ophthalmicus — is sent to the organs of 
the anterior dorsal pit line, a separate, smaller branch being sent 
from it to each organ of the line. This nerve alone, or together 
with the branch to organ 7 supra-orbital, which Jeaves the main 
nerve close to it, probably represents the branch which, accord- 
ing to Wright (No. 26, p. 483), supplies the organs of the trans- 
verse commissure in Mustelus. Wright is inclined to consider 
