edge of th e cartilaginous prootic bridge and then runs backward beneath th a t bridge to enter and
supply the rectus externus. In the adults both of Scorpaena and Trigla, th e nerve perforates th e
bony prootic bridge to reach its muscle. In Cottas octodecimospinosus it runs over th e anterior edge
of th e bony bridge. In small specimens of Dactylopterus it enters the trigemino-facialis chamber
through th e facialis foramen, and traversing th a t chamber ventra l to all th e other nervous structures
issues by th e trigeminus opening of th e chamber and then immediately enters its muscle.
T R I G E M I N O - F A C I A L I S C OMP L E X .
This complex has, in Scorpaena, five apparent roots, as Stannius has s tated th a t it has in
Trigla, b u t two of these roots, th e lateralis-roots, may issue as a single root from th e medulla and
then immediately separate. These two lateralis roots and the motor facialis root are so closely applied,
a t the ir origin, th a t they appear almost as a single root, and are so shown in figure 28. In th a t figure,
furthermore, th e communis root appears crowded down between th e trigeminus and th e lateralis
and motor facialis roots, this n o t being its position in sections of young specimens.
My sections did not permit of more th a n a very general determination of th e central origin
and peripheral distribution of th e fibers of the several roots, b u t comparison with Menidia will show
th a t these determinations are probably correct.
a. R o o t s a n d G a n g l i a o f t h e C o m p l e x .
The anterior one of th e five roots of th e complex -is th e so-called root of th e trigeminus, and
it contains both motor and general cutaneous fibers. The motor fibers lie on the dorso-mesial aspect
of th e root as it emerges from th e medulla. The fibers of th e deep sensory root lie lateral to these
motor fibres, the two bundles of fibers extending dorso-mesially into th e medulla, lying close together,
and certainly having their principal origins in groups of cells th a t represent respectively th e chief
sensory and motor nuclei of th e trigeminus. The remaining, v entral fibers of th e ro o t enter th e
spinal V tra c t. The motor fibers, having issued from th e medulla, soon cross, as in Menidia, to the
ventral surface of th e root, and so continue during the ir intracranial course. The entire root, running
forward and laterally, lies a t first, in sections, mesial to th e other roots of the complex and th en between
th e lateralis trigemini and lateralis facialis roots, ventral to the former and dorsal to th e la tte r.
While still in th e cranial cavity it gives off the profundus root. I t then traverses th e trigeminus
foramen, enters th e trigemino-facialis chamber, and there immediately swells into the large trigeminus
ganglion, which, in my young specimens, seems wholly distinct and separate from any other
portion of th e ganglionic complex excepting only ;the large related sympathetic ganglion. The ganglion
lies almost wholly in the trigemino-facialis chamber, a small collection, only, of cells being found
on th e ventral surface of th e root ju s t before it issues through its foramen; these cells being connected
with th e main ganglion by a small ganglionic strand which traverses th e foramen. The ganglion
thus lies almost entirely in th e cranial wall and n o t in the cranial cavity, all th e other ganglia of the
complex, excepting only th e related sympathetic ganglion, lying in th e cranial cavity itself.
The profundus root arises from th e sensory portion of the trigeminus root, on its antero-mesial
aspect, and running aritero-laterally enters th e ..intracranial profundus ganglion which lies slightly
antero-mesial to the large stalk formed b y th e other roots of th e complex.
The n ex t posterior root of th e complex is th e motor root of th e facialis. This root emerges
from th e medulla close to th e anterior root of th e nervus acusticus, almost as a p a rt of th a t root,
and directly anterior to the low swelling of the acusticus p a rt of th e tuberculum acusticum; the
anterior root of th e acusticus spreading, ánd entering the medulla both dorsal and v entral to th e level
of the point of exit of th e motor root of the facialis. After th e root emerges from the medulla it lies
dorso-anterior to th e anterior root of the acusticus, between it and th e overlying lateralis facialis
root, b u t it soon passes up along the lateral surface of the la tte r root and reaches its dorsal surface.
There it continues forward closely applied to th e lateralis facialis and issues, with th a t nerve, through
th e facialis foramen. As th e two nerves pass through the foramen, of shortly before, they receive a
large bundle of fibers from th e communis ganglion, th e three components together forming the
truncus facialis. This truncus does not traverse th e trigeminus ganglion, passing postero-ventral
to th a t ganglion. As in Menidia, it contains no general cutaneous component.
The next posterior root is the communis root. This root leaves th e medulla almost directly
dorsal to th e motor facialis root, its point of origin lying immediately dorsal to th e low, acusticus
swelling of th e tuberculum acusticum, and immediately anterior to th e low, lateralis swelling of
the same structure. Immediately after issuing from th e medulla i t lies wedged in between the
lateralis trigemini and lateralis facialis roots, and, anterior to th a t point, lies lateral and then ventral
to the trigeminus root as th a t root passes between the two lateralis roots. I t then swells into a large
pear-shaped intracranial ganglion, the large -end of th e p ear directed antero-laterally, and the ganglion
occupying the ventral or ventro-mesial portion of the large root-stalk of th e complex. From the
anterior portion of this ganglion, three bundles, or groups of sub-bundles of fibers arise, their arrangement
being somewhat different on th e two sides of the one specimen in which they were traced. One
of these bundles is the ramus palatinus facialis which runs downward in the cranial cavity and, perforating
th e base of th e prootic bridge, enters th e myodome. A second one of the three bundles is
a group of sub-bundles which traverses the trigeminus foramen; containing two separate sub-bundles
on one side of th e specimen and three on the other. One of these sub-bundles enters and traverses
th e trigeminus ganglion, going mainly if not entirely to th e ramus oticus; th e other one or two sub-
bundles traversing th e ganglion to enter th e truncus maxillo-mandibularis trigemini. The third
bundle th a t arises from th e main ganglion traverses th e facialis foramen and it was single on one side
of my specimen b u t double on th e other. On th e single side th e entire bundle entered the truncus
facialis, a small branch being immediately sent to Jacobson’s anastomosis. On th e double side, one
of th e two sub-bundles went to the truncus facialis and Jacobson’s anastomosis, the other sub-bundle
running upward in th e trigemino-facialis chamber and entering th e truncus maxillo-mandibularis.
This la tte r arrangement was also found on one side of the adult specimen used for figure 28, and
hence is probably not unusual.
The communis root of Scorpaena thus differs from th a t of Menidia only in th a t two separate
bundles of fibers, instead of a single one, go to th e truncus maxillo-mandibularis. Whether both
bundles go to th e ramus maxillaris, or one to th a t ramus and th e other to th e ramus mandibularis,
I could not determine. Scorpaena further differs from Menidia in the absence of any intracranial
recurrent communis nerves, and Trigla, Lepidotrigla and Dactylopterus all agree with Scorpaena
in this respect. In Cottus, on the contrary, there is an important intracranial recurrent branch.
The n ext two roots of the complex, in Scorpaena, th e two th a t have th e m ost posterior a pparent
origin from th e medulla, are the roots of th e lateralis trigemini and lateralis facialis nerves. These
two roots arise as a single root from the tuberculum acusticum immediately posterioij to the communis
root and immediately dorso-posterior to the anterior root of the acusticus, between th a t root and
Zoologioa. Heft 57. <<