-of and does not traverse the trigeminus ganglion. Immediately after issuing from the skull it gives
off a small branch which turns upward and inward and, perforating th e alisphenoid, enters the cranial
cavity. There it runs upward along the inner surface of the skull, lying in the membranous tissue
th a t lines th a t surface, and, piercing th e frontal, reaches th e small sixth organ of th e supraorbital
canal, which it innervates. I t is accompanied by a delicate branch of th e trigeminus, apparently
of general cutaneous origin, as already stated, b u t this branch could n o t be separately traced in the
cranial cavity. In Lepidotrigla th e same mixed nerve is found. In Cottus scorpius a similar nerve
is also found; b u t in th e sections of this fish th e nerve is lost beneath th e terminal tube of th e supraorbital
canal, and no organ is evident in th a t tube. In th e adult Cottus octodecimospinosus the
nerve is found innervating th e terminal organ of th e supraorbital canal, as in Scorpaena and Lepidotrigla.
Slightly posterior to this nerve, in Cottus, and having a closely parallel course, there is
a communis nerve which has an intracranial origin from th e communis ganglion, and from there
runs upward and then backward along th e side wall and roof of th e cranial cavity. Whether or not
this nerve anastomoses with an intracranial branch of th e vagus could n o t be determined in Cottus
scorpius, b u t in Cottus octodecimospinosus it does anastomose with such a branch and then issues
near the hind end of th e skull; this seeming to indicate th a t it must form th e anastomosis in Cottus
scorpius also. The nerve is accordingly the ramus lateralis trigemini of Stannius’s descriptions, called
by Herrick, in his descriptions of Menidia, th e facialis root of th e ramus lateralis accessorius. I t is
said b y Stannius not to be found in Trigla, which I confirm. I t is also not found in Scorpaena or
Dactylopterus.
In th e Cod, the facialis root of the lateralis accessorius is said by Herrick (’00) to be present
and to be accompanied by a few coarse fibers from the lateral line ganglion, which fibers would accordingly
seem to correspond to th e branch to organ 6 supraorbital in Scorpaena. Whether or n o t this
la tte r branch of Scorpaena is represented in Pleuronectes by any p a rt of Cole & Johnstone’s (’01,
p. 128) ramus lateralis accessorius facialis, I can n o t decide. In Ameiurus it is represented in Herrick’s
(’01) branch N. 5, which has a wholly intracranial course until it pierces the frontal to reach its organ;
a branch of th e nerve going to th e anterior head line of p it organs.
The ophthalmicus lateralis, in Scorpaena, having given off th e branch to organ 6 supraorbital,
runs forward between th e two strands of th e ophthalmicus trigemini and soon gives off a branch
which, running upward, separates into two p a rts and supplies th e fourth and fifth organs of th e suprar
orbital canal. This branch, in th e several specimens of Scorpaena examined, and as already stated,
sometimes separated into its two parts before it pierced th e frontal, sometimes so separated while in
its canal in th e frontal, and, in one specimen, entered th e supraorbital canal as a single nerve which
then, lying in the canal, supplied, first, organ No. 4 and then organ No. 5. After giving off this branch
th e ophthalmicus lateralis continues forward, sends branches in succession to th e th ird and second
supraorbital organs, and th en supplies and terminates in th e first organ of th a t line.
The ramus oticus, in Scorpaena, separates from th e buccalis while th a t nerve is traversing
th e trigeminus ganglion, and issues from the ganglion as an independent lateralis branch b u t accompanied
b y two bundles of fibers one of which is of general cutaneous and the other of communis origin.
This la tte r bundle issues from the cranial cavity through th e trigeminus foramen, and, so far as my
quite unsatisfactory sections show, contains all th e communis fibers th a t go to the trigeminus excepting
those th a t accompany th e truncus maxillo-mandibularis. These three bundles of fibers, united
to form a single nerve, run upward and laterally along the hind wall of th e orbit and, traversing the
oticus canal in the sphenotic, issue on the dorsal surface of the skull beneath the frontal bone. A
lateralis branch is th en sent to th e infraorbital organ in the postfrontal, and a second branch to the
organ in th e pterotic, these two branches apparently containing all the lateralis fibers of the nerve.
The remainder of th e nerve then runs backward beneath the dermal bones of th e top of the skull,
enters the temporal fossa and there runs into and anastomoses with the supratemporal branch of the
vagus, branches being sent backward, from th e united nerves, along th e dorsal surface of th e trunk.
As th e main nerve passes dorso-mesial to th e dilatator groove, it lies very close to th a t groove, and
may even be exposed in the bottom of it. A venous vessel, a branch of th e external jugular, here
perforates th e bottom of the groove and joins th e nerve, accompanying it in its further course toward
th e hind end of th e skull.
In Lepidotrigla the ramus oticus is a purely lateralis nerve, and is n o t continued posteriorly
beyond the second organ in th e pterotic, th e pterotic in this fish lodging two organs innervated
by th e oticus, without an intervening primary tube. This condition of these two organs in this fish
would seem to represent a stage in the reduction of th e two organs here found normally developed
in Amia and certain other fishes to th e one organ found in Scorpaena and still other fishes; a reduction
stric tly similar to th a t th a t is taking place in the 4 th. and 5 th. supraorbital organs both of Lepidotrigla
and of Scorpaena. In Lepidotrigla, th e general cutaneous and communis fibers th a t accompany
th e oticus in Scorpaena are represented (or replaced) by fibers th a t do not traverse the oticus
canal; and this is also the condition in Amia, in which fish the ramus oticus is also a purely lateralis
nerve while the ophthalmicus lateralis branch th a t supplies the anterior head line of p it organs is
accompanied by fibers th e character of which was n o t determined in my work on th a t fish, b u t which
have an apparent origin and distribution similar to th a t of the fibers th a t accompany th e oticus in
Scorpaena.
In Dactylopterus the oticus lateralis is accompanied by a bundle of general cutaneous fibers,
and apparently by those fibers only.
In Ameiurus, the ramus oticus is said by Herrick (’01) to contain lateralis, general cutaneous,
a n d communis fibers, to have an intracranial origin, and, running upward, to pierce the roof of the
skull; which would seem to mean th a t it does n o t first issue in the hind end of the orbit before
entering and traversing the oticus canal. In Menidia the ramus oticus is said by Herrick (’99) to
oontain lateralis and general cutaneous fibers, and to correspond to th e ramus oticus plus the external
buccal of Cole’s descriptions of Gadus: th a t is, its lateralis fibers innervate not only the latero-sensory
organs in the postfrontal and pterotic sections of the main infraorbital canal b u t also the organ
in th e dorsal postorbital bone. The ramus oticus of Menidia, minus the external buccal portion, is said
to traverse a canal in th e sphenotic and, as ju s t above stated, it contains both lateralis and general
cutaneous fibers. This intimate association, in this nerve, of fibers th a t are considered by the author to
have a central origin in the facialis and trigeminus segments, respectively, leads Herrick to conclude
th a t the oticus „was probably originally th e dorsal ramus of the facial nerve to which lateralis elements
have been secondarily added and whose general cutaneous portion has, like th a t of th e profundus
nerve, been cenogenetically fused with the Gasserian ganglion“ . That is, it is assumed, in
this statement, th a t general cutaneous fibers th a t originally issued from th e brain by three distinctly
different apparent roots, and th a t belonged to three distinctly different b u t adjacent metameric
segments, have come, in Menidia, to issue by a single apparent root and from a single, unsegmented
•cerebral center; this being the result of a central condensation so complete th a t all traces of th e ori