3. S U S P E N S O R I A L A P P A R A T U S A N D M A N D I B L E .
The PREOPERCULAR is a stout bone with dorsal and ventral limbs lying a t somewhat more
th a n a right angle to each other. In the ir n a tura l positions th e dorsal limb is directed dorso-anteriorly
and the ventral limb ventro-anteriorly. The dorsal portion of th e dorsal limb rests against and is
firmly bound by tissue to th e grooved hind edge of the hyomandibular, its dorsal end n o t extending
beyond the opercular process of th a t bone. The ventral portion of the ventral limb rests against
and is firmly bound to th e grooved postero-ventral surface of the posterior process of the quadrate.
Between these two portions of the preopercular a large and th in web of bone extends across th e angle
between the two limbs and supports, on its internal surface near its ventral end, th a t p a rt of the
hyomandibulo-symplectic interspace of cartilage on which lies the articular facet for the interhyal.
Dorsal to th a t facet, th e web of bone is thickened to form a process-like portion, and th e edge of this
portion is bound b y tissue to th e hind edge of the ventral portion of th e hyomandibular. A t the dorsal
end of th e web there is an incisure, through which, between th e preopercular and th e hind edge of the
hyomandibular, the ramus hyoideus facialis passes from the outer to the inner surface of th e apparatus.
The large and well known preopercular spine of the fish extends posteriorly in th e direction of
th e ventral limb of the bone, and almost as a posterior continuation of th a t limb. A second one of
th e three preopercular spines lies directly v entral to this large one, either parallel with it, or directed
ventro-poste.riorly a t an angle to it. The th ird preopercular spine arises from th e ventral edge of the
ventral limb of th e bone, close to its anterior end. The bone is traversed its full length b y th e preopercular
latero-sensory canal and lodges five sense organs of th a t canal.
The HYOMANDIBULAR has anterior and posterior heads for articulation with th e pranium,
and a very s to u t head for articulation with th e opercular. The shank of the bone is relatively broad
and thin, and th e longitudinal ridge on its outer surface is short, b u t stout. The bone is traversed
by a facialis canal, which opens on the outer surface of th e shank anterior to th e longitudinal ridge,
and also by a short branch canal which opens on the outer surface of the bone posterior to the ridge.
A large web of bone fills th e angle between th e anterior articular head and th e shank of th e bone,
and is in contact with and is firmly bound by tissue to th e hind edge of the metapterygoid.
The SYMPLECTIC has a broad flat dorsal end, and from there tapers rapidly into a long
rod-like ventral portion which lies in th e symplectic groove on the inner surface of the. quadrate.
There is a canal along its anterior edge, between it and the anterior edge of th e symplectic groove
on the quadrate, which transmits the ramus mandibularis intemus facialis.
The QUAD RATE has a stoiit and long posterior process which is separated from the body
of th e bone by a shallow incisure. Anterior to th e dorsal portion of the process, between it and the
symplectic, there is a long oval opening which transmits th e ramus mandibularis extemus facialis
and th e arteria hyoidea. The posterior process of th e quadrate is so long th a t it almost completely
shuts th e preopercular off from bounding participation in this opening. Along the anterior edge of
the base of the process there is, on the inner surface of the body of th e quadrate, a symplectic groove.
From th e inner surface of th e anterior edge of the bone a sto u t ligament arises and running forward
joins th e tendon A2A3-Aw.
The METAPTERYGOID is large ancTflat, and without evident flanges on its hind edge. This
edge of the bone is however in contact with the anterior edge of th e flange on the anterior edge of
th e hyomandibular, this Contact being a characteristic of the flanges of the metaptèrvgoids of Scor-
paena and Sebastes, and not of th e bodies of those bones. The bone is perforated, in Cottus, in its
dorso-posterior portion, by a foramen which transmits th e external carotid arte ry from the external
to th e internal surface of the palato-quadrate apparatus. Immediately internal to th e foramen,
th e carotid falls into th e arteria hyoidea a t a sharp bend in th a t artery, the arteria hyoidea there
turning almost directly backward to enter th e opercular hemibranch. The arteria hyoidea, ventral
to this bend, lies a t first along th e internal surface of th e metapterygoid, b u t comes to th e outer surface
of the apparatus through a large fenestra between the metapterygoid, hyomandibular and symplectic.
I t th e n crosses th e external surface of th e symplectic and passes to the internal surface of the
apparatus through th e opening between th e symplectic and preopercular, the mandibular artery
being here given off, as in Scorpaena. The relations of these two arteries to the metapterygoid would
th u s be th e same as those in Scorpaena, if those pa rts of the hind edge of th e bone of Cottus th a t
lie dorsal and ventral to the foramen for the external carotid represented respectively th e internal
and external flanges on th e hind edge of th e bone of Scorpaena; and this is certainly the case, the
ventral edge of th e internal flange abutting against and fusing with the dorsal edge of the external
flange, and th e foramen for th e carotid, in Cottus, representing the greatly reduced Y-shaped space
between th e two flanges in Scorpaena. The relatively large fenestra th a t transmits the arteria hyoidea
is then th e homologue of th e small opening th a t transmits th a t artery in Scorpaena.
The efferent pseudobranchial arte ry is as in Scorpaena.
. The ECTOPTERYGOID and ENTOPTERYGOID are in normal position, the la tte r bone
being relatively long.
The PALATINE has a short body and a long b u t low ventral flange, this flange being wholly
without te e th and its hind end being prolonged posteriorly in a tapering point which lies against
th e ventral surface of th e dorsal limb of th e ectopterygoid. On th e lateral surface of the body of
th e palatine, anterior to the base of th e process-like posterior extension of its ventral flange, there
is a deep U-shaped depression, the legs of the U being directed posteriorly. In the posteriorly directed
hollow of this U, the process on the mesial edge of th e articular -head of the lachrymal is received,
a n d is firmly bound to it by tissues, some slight motion between th e pa rts being possible. The body
o f th e palatine is in synchondrosis posteriorly with a well formed rod of cartilage which lies along
th e dorsal surface of the dorsal limb of the ectopterygoid and connects the body of th e palatine with
th a t portion of the palato-quadrate cartilage th a t lies between the quadrate and metapterygoid.
The maxillary process of the palatine is s to u t and its distal end is expanded into a broad flat
portion which rests upon and is firmly bound to th e dorsal surface of th e maxillary. At the base
of the process there is a small process directed dorso-mesially. This process is strongly bound by
tissue to th e lateral edge of th e ethmoid cartilage, b u t does n o t have articular contact with th a t
cartilage. In Scorpaenichthys this process is large, and articulates with a large articular surface
o n the lateral edge of th e ethmoid cartilage. In Cottus, the lateral surface of the little process gives
insertion to the rostro-palatine ligament. The vomero-palatine ligament is relatively long, arises
from th e hind edge of the raised, toothed portion of the vomer, and running postero-laterally is inserted
on the internal surface of the body of the palatine.
, The anterior and posterior ethmo-palatine articulations are thus both wanting in Cottus, the
posterior articulation being replaced by the articular connection of the palatine with thè lachrymal.