triangular, with curved edges. Its ventral edge fits onto th e outer surface of the second infraorbital,
its hind edge overlapping and resting upon th e anterior edge of th e preopercular, and extending
nearly to its dorsal end. Its concave anterior edge forms th e posterior boundary of the orbit. Its
dorsal end does n o t quite reach the láteral edge of th e postfrontal. These two bones are traversed
b y th e main infraorbital canal, and each lodges one organ of th a t line.
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 QUADRATE has th e usual shape, with its ventral corner enlarged to form th e articular
head for th e mandible. Its antero-ventral edge is bevelled, and fits into the grooved hind edge of the
ventral limb of th e ectopterygoid. Its ventro-posterior edge is greatly thickened, is prolonged dorso-
posteriorly in a short sharp posterior process, and between this process and th e body of the bone,
on the internal surface of th e element, there is a large symplectic groove. The ventro-posterior surface
of th e posterior process is grooved and fits against and is firmly bound to th e anterior edge of the ventra
l end of th e preopercular. The lateral surface of th e process is raised in a large and ta ll ridge, the
outer surface of which is roughened and gives support to, and is firmly bound to, th e ventro-posterior
corner of th e second infraorbital bone. The dorso-posterior end of this raised portion fits into a small
notch in th e anterior edge of th e preopercular. Between this raised portion of th e process and the
external surface of the body of th e quadrate, there is a large depression which seems to have no special
morphological significance.
The METAPTERYGOID has its dorso-anterior edge b en t slightly inward, and has lateral
and mesial flanges along its hind edge. The mesial flange is a small one excepting a t its dorsal end
where it is prolonged into a process which meets, or almost meets a flat process th a t projects antero-
ventrally from th e anterior edge of th e th in web of bone th a t fills th e space between th e anterior
a rticular arm of the hyomandibular and th e shank of th a t bone, and is bound to th a t process by
fibrous tissues. Ventral to this process-like portion, th e hind edge of th e mesial flange is connected
by s, wide sheet of membrane with the shank of the hyomandibular. The lateral flange projects
postero-laterally a t a slight angle to th e body of th e bone, and reaches, or overlaps slightly, and is
a ttached to the outer surface of th e ventral end of th e shank of the hyomandibular. The ventral
corner of this lateral flange approaches, or may even reach and re st upon th e outer surface of the
cartilaginous interspace between th e hyomandibular and symplectic; and there is, in th e corner
of.the flange, an incisure which, with th e adjoining cartilage and th e hyomandibular, forms a foramen
which transmits th e arteria hyoidea.
The ECTOPTERYGOID has th e usual two limbs lying a t an obtuse angle to each other,
th e dorso-anterior limb being a large plate th e dorsal edge of which is grooved. This groove lodges
th e ventral edge of the anterior end of th e entopterygoid, and also th a t p a rt of the palatine bone
and cartilage th a t forms th e posterior ethmoid process of the apparatus, th e lateral edge of th e groove
being a ta ll plate which lines th e lateral surface of th e palatine cartilage and may even project dorso-
posteriorly slightly beyond th e cartilage. The anterior edge of this p a rt of the ectopterygoid is
somewhat jagged, and suturates with th e hind edge of th e ventral flange of th e palatine. The ventro-
posterior limb of th e bone is grooved on its posterior surface and fits against th e antero-ventral edge
of th e quadrate.
The ENTOPTERYGOID is small, and its ventral half lies closely against the inner surface
of a p a rt of the cartilage of the apparatus th a t lies between the metapterygoid and the ectopterygoid,
along the dorsal edgè of th e quadrate. The. dorsal half of the bone projects beyond the cartilage,
is concave on its outer and convex on its innér surface, and lies against the under surface of and gives
insertion to a portion of th e adductor arcus palatini. The anterior end of the bone rests in the grooved
dorsal edge of th e dorsal limb of the ectopterygoid, its posterior end n o t quite reaching, in small
specimens, th e anterior end of the metapterygoid..
The PALATINE has a body, a maxillary process, and a sto u t and large ventral flange of dermal
origin. The hind edge of th e v e n tra l flange is jagged and suturates with the anterior edge of the
dorsal limb of th e ectopterygoid. The hind end of th e body of th e bone is in synchondrosis with the
cartilage of th e posterior ethmoid process of th e apparatus. The maxillary process of the boné curves
slightly antero-mesially, is flattened on its dorso-lateral surface, and there rests against and is firmly
bound to the internal surface of the dorso-anterior edge of the lachrymal. A small eminence a t the
base of the m axillary process gives insertion to th e rostro-palatine ligament, and immediately posterior
to this process there is an obliquely transverse facet which articulates with the anterior palatine
procèss of th e ethmoid cartilage. The vomero-palatine ligament is unimportant. The antèrior end
of the maxillary process of the bone is capped with cartilage and articulates with th e dorsal surface
of th e maxillary, in th e angle between the. la te ra l surface of the ascending process and th e shank
of th a t bone. The posterior portion of th e body of the palatine, and the cartilage th a t forms th e
posterior ethmoid process of the apparatus, are firmly bound to th e lachrymal, in the manner already
described. Between this posterior p a rt of the palatine and th e base of its maxillary process, the dorsolateral
surface of th e body of the bone is slightly hollowed, this hollow lodging th e lateral half of
the nasal sac.
The palato-quadrate, as a whole, forms a plate which is slightly concave on its ectal surface,
and th e two anterior infraorbital bones together form a plate which is slightly concave on its ental
surface. These two plates are firmly bound to each other by their anterior edges, while by their
posterior edges they are firmly bound to the preopercular and hyomandibular. The two plates
together thus form a flat, hollow, trapezoidal structure, open both dorso-mesially and ventro-laterallv
by large and relatively narrow openings. The space enclosed between the two plates is, in the recent
state, almost completely filled by the adductor mandibulae muscle.
The HYOMANDIBULAR is cross-shaped, the arm of th e cross lying obliquely to th e shank.
The summit of the longitudinal ridge on the outer surface of the shank projects forward, and so
gives to th e anterior surface of th e bone a grooved appearance. The dorsal portion of this forwardly
projecting ridge gives support, on its lateral surface, to th e fourth bone of th e infraorbital series.
The shank of th e bone is traversed b y a facialis canal, thè ventral opening of th a t canal lying anterior
to the longitudinal ridge. From this canal a single branch ca-nal arises, and running postero-ventrally
opens on the outer surface of th e bone, near th e ventral end of the th in web of bone th a t fills the
space between the opercular process and th e ventral portion of th e shank of th e bone. I t transmits
a nerve destined to innervate th e two dorsal ones of the latero-sensory organs in the preopercular,
a single canal thus here replacing th e two canals found in Scorpaena. A foramen leads directly
from th e main canal for the facialis onto th e anterior surface of th e bone, b u t it only transmits
a blood vessel.