No. 3.] WUSCLES AND NERVES IN AMIA CALVA. 745 
The branch that innervates the four divisions of the levator 
maxillae superioris arises from the base of the nerve, or even 
from the main truncus maxillaris, and may be double through- 
out its entire length. 
Certain branches of the ramus have a peculiar and circuitous 
course, and are distributed to regions where terminal buds 
abound. One of these branches becomes a mandibularis inter- 
nus trigemini, distributed to the inner surface of the mandible ; 
another goes to the tissues of the mouth cavity near the upper 
end of the ceratohyal; and two others pass under the ramus 
mandibularis externus facialis, and are distributed to the outer, 
ventral surface of the head, where they form anastomoses with 
branches of the ramus hyoideus facialis. These branches of 
the trigeminus are all prespiracular nerves, and are all dis- 
tributed to regions where terminal buds are found. The 
mandibularis internus trigemini, with or without other of these 
special branches, seems to correspond to the inferior branch of 
the palatinus facialis in Protopterus and Polyodon, and to be 
the homologue of the chorda tympani of higher animals. 
19. The truncus hyoideo-mandibularis facialis arises largely 
from the posterior commissure of the main trigemino-facial 
ganglion. Its rami opercularis and hyoideus innervate the 
adductor and levator muscles of the hyoid arch, the hyohyoi- 
deus, and probably also the superior division of the genio- 
hyoideus, and a part, at least, of the inferior division of that 
muscle. Its ramus mandibularis externus contains all the 
lateral fibres of the nerve, and innervates the sense organs of 
the operculo-mandibular portion of the lateral canal system. 
Its ramus mandibularis internus is distributed to the inner 
surface of the hyoid and mandibular arches. As this last nerve 
is a postspiracular nerve, it seems impossible that it should be 
the homologue of the chorda tympani, which is apparently a 
prespiracular nerve. 
No branches of any of these nerves could be traced definitely 
to the pseudobranch. 
20. The ramus palatinus facialis arises, in larvae, from the 
median, or fasciculus communis, portion of the main trigemino- 
facial ganglion. It separates into an anterior and a posterior 
