ginal subdivisions of th e root and center have been lost. The equally evident assumption th a t all
th e lateralis fibers associated with trigeminus nerves are trigeminus ones cenogenetically fused with
th e lateralis fibers of th e facialis segment, is not made; and y e t this assumption has apparently much
more evidence in fact, for th e lateralis trigemini and lateralis facialis fibers here, and in many other
fishes also, arise by separate apparent roots and each have an independent ganglion. Johnston, in
a recent work (’05 a, p. 222), does make what is practically th e equivalent of this assumption, for
he there says th a t it seems probable to him th a t th e supraorbital, infraorbital and hyomandibular
latero-sensory lines belong respectively to th e profundus, trigeminus and facialis segments. He does
not, however, say th a t th e nerves innervating th e three lines must also belong to those same segments,
and such may not be his meaning.
One other point relating to this same subject can here be mentioned. In many teleosts, as
already stated, a stran d of general cutaneous fibers, arising from the Gasserian ganglion, joins th e
truncus hyoideo-mandibularis facialis. These fibers join th a t nerve extracranially in Scorpaena,
Menidia and many other fishes, b u t intracranially in Pleuronectes (Cole & Johnstone, ’01, p. 124).
Here th en is another instance in which th e cenogenetic fusion of fibers belonging originally to th e
trigeminus and facialis segments might b e suggested, b u t neither Herrick nor Johnston (’05 a) even in timate
it; and yet, in Amia, Kingsbury (’97), before th e publication of Herrick’s work, had s tated th a t
general cutaneous fibers issue from th e brain in th e root of th e facialis in all th e specimens of th a t
fish th a t he had examined, and Johnston (’05 b), since th e publication of Herrick’s work, says th a t
th ey also issue in th a t ro o t in Petromyzon.
And if th e assumption of cenogenetic fusions can be made either for th e general cutaneous
or lateralis fibers of th e complex, why can it n o t also be made for th e communis fibers? Those fibers
th en would, in large p a rt a t least, normally belong to th e nerves with which th ey are associated,
certain juxtapositions perhaps being possible where there are no skeletal elements to prevent them;
and th e varying q uantity of communis fibers in th e several trigeminus and facialis nerves would
be due to a corresponding variation in th e development of th e terminal organs innervated by either nerve.
Returning now to th e descriptions, the buccalis facialis traverses, in all th e fishes examined,
th e trigeminus ganglion, and, accompanying th e ramus maxillaris trigemini, supplies th e organs of
th e post- and sub-orbital portions of th e main infraorbital canal.
The truncus facialis, in Scorpaena, Lepidotrigla and Dactylopterus contains motor, lateralis
and communis fibers, th e la tte r fibers, in all these fishes, traversing th e facialis foramen and joining
th e other fibers of th e truncus either as th ey are traversing, or after they have traversed th e same
foramen.
The ramus palatinus contains communis fibers only, and in Scorpaena it usually has an independent
origin from th e communis ganglion. In the 55 mm Scorpaena, it had such an origin on one
side of th e head, while on th e other side it arose from th e base of th e bundle of communis fibers sent
to the trigeminus ganglion. Turning downward in th e cranial cavity, th e nerve traverses the palatine
canal in th e prootic, enters th e myodome, and, turning forward, enters th e orbit along its floor; its
further course n o t being traced. In Cottus, th e palatinus has a course similar to th a t in Scorpaena,
b u t in Trigla, Lepidotrigla and Dactylopterus it does not separate from th e other communis fibers
u ntil after those fibers have traversed the facialis foramen. There it tu rn s forward and downward
along the floor of the trigemino-facialis chamber, issues through th e trigeminus opening of th a t
chamber, and, traversing the myodome of th e fish, enters th e orbit.
The next branch of the truncus facialis, in the 55 mm Scorpaena, is given off as the truncus
traverses its foramen, and contains communis fibers only. Turning downward and backward it issues
through th e facialis opening of the trigemino-facialis chamber and then almost immediately joins
and anastomoses completely with the ramus anterior of the nervus glossopharyngeus. The nerve
so formed is Jacobson’s nerve. I t runs antero-ventrally along th e dorso-anterior aspect of th a t p a rt
of th e hyoid cleft th a t lodges th e opercular hemibranch, and is distributed to th a t hemibranch and
to th e adjacent tissues on th e anterior surface of th e cleft, delicate branches of the nerve accompanying
both the efferent and afferent arteries of th e hemibranch. In both Cottus and Lepidotrigla this nerve
is found in almost identical conditions, and it doubtless also is in Dactylopterus, b u t in this la tte r
fish it was n o t traced beyond th e point of its anastomosis with the glossopharyngeus. The fibers
of the glossopharyngeus all run distally with the facialis fibers, none of them turning proximally
along the facialis nerve, as I was led to suppose might be th e case in Scomber.
Immediately before or after the facialis branch to Jacobson’s nerve arises from th e truncus
facialis, th a t truncus receives, in both Scorpaena and Lepidotrigla, a communicating branch or
branches from th e facialis sympathetic ganglion, this connection doubtless existing also in the other
fishes of th e group b u t n o t there being traced.
After giving off th e nerve to Jacobson’s anastomosis, th e facialis, in Scorpaena and Lepidotrigla,
sends a motor branch to th e adductor arcus palatini, and then a branch to th e adductor hyo-
mandibularis; this la tte r branch also innervating th e adductor and levator operculi. These two nerves
together form th e ramus opercularis profundus of Herrick’s nomenclature. The branch th a t goes
to the adductor hyomandibularis is joined posteriorly by and anastomoses with a branch of the supra-
temporal branch of th e nervus vagus, certain of the fibers of th e vagus running proximally along
the fibers of th e opercularis profundus and the two nerves thus appearing as a complete and uninterrupted
circuit. In Cottus and Dactylopterus th e opercularis profundus is also found, b u t its anastomosis
with a branch of the vagus was not traced.
The truncus facialis, in Scorpaena and Lepidotrigla, is then joined by th e communicating
branch from the trigeminus ganglion and becomes the truncus hyoideo-mandibularis of Stannius’
nomenclature. This nerve continues laterally and slightly downward and enters the facialis canal in
th e hyomandibular, lying, in its course, postero-dorsal to th e adductor arcus palatini and anterior to the
adductor hyomandibularis and to all of the levator muscles of th e branchial arches. As it enters its canal
in th e hyomandibular, a branch is sent backward in the small branch canal in the hyomandibular, and,
separating into two parts, innervates the two dorsal latero-sensory organs in the preopercular canal.
This small branch is th e ramus opercularis superficialis of Herrick’s nomenclature, and it was traced
in th e dissections and not in the sections of Scorpaena; the sections here being quite imperfect. In
th e dissections no branch could be found distributed to the outer surface of the operculum, such as
Herrick describes in Menidia, b u t in Lepidotrigla this branch was found, though the character of its
fibers could not be determined. In Menidia these fibers of th e nerve are said by Herrick to be pa rtly
general cutaneous and partly lateralis. These la tte r fibers are said to supply certain naked cutaneous
sense organs lying on th e outer surface of th e operculum, these organs being of th a t intermediate
type between pit-organs and terminal buds which are always puzzling to every observer. Herrick
concludes th a t these organs must, because of their innervation, belong to the lateral line ra the r than
the communis system, a conclusion I am not prepared, from th e facts so far presented, to accept.
In th e Cod the corresponding fibers of this nerve are said by Herrick (’00) to probably be wholly
Zoologies. Heft 57.