746 ALETS. iVor. Xi. 
portion, both of which are distributed to the upper and lateral 
surfaces of the mouth cavity. Both portions form anastomoses 
with branches of the ramus maxillaris superior trigemini, and 
the anterior portion, at its anterior end, pierces the basis cranii 
to reach the upper surface of the anterior end of the chon- 
drocranium. One of the branches of this nerve was traced 
into one of the large premaxillary teeth. 
21. The nervus acusticus arises, in larvae, from the summit 
of the tuberculum acusticum by three distinct roots, on each 
of which a somewhat distinct part of the large acoustic gan- 
glion is formed. The more dorsal of the three roots forms the 
posterior root of the nervus, and gives origin to the ramus 
cochlearis. The other two roots together form the anterior 
root of the nervus, and give origin to the ramus vestibularis. 
The two nerves innervate the cristae ampullae as in other 
fishes. 
No ductus or saccus endolymphaticus could be recognized 
in any of the specimens examined, old or young. 
22. The nervus lineae lateralis vagi arises, in larvae, imme- 
diately posterior to the tuberculum acusticum. It either 
traverses in part, or is traversed by, the root of the nervus 
glossopharyngeus, an important interchange of fibres there 
taking place, the fibres apparently running from the nervus_ 
lateralis into the glossopharyngeus, and there giving origin to 
the so-called dorsal root of that nerve. 
The nervus issues from the cranial cavity with the nervus 
vagus through the vagus foramen, enters its own ganglion, and 
is then distributed to the lateral sense organs of the supra- 
temporal cross-commissure, and to those of that part of the 
lateral sensory system that lies posterior to that commissure. 
23. The nervus glossopharyngeus, immediately after its exit 
from the brain, pierces the median, membranous wall of the 
auditory cavity and traverses that cavity, lying, in its passage, 
behind the membranous ear, between the sacculus and the 
sinus utriculi posterior, and between the two terminal branches 
of the ramus cochlearis acustici. It apparently receives fibres 
both from the root of the nervus lineae lateralis and from the 
ramulus ampullae posterioris, the fibres so received going to 

