latero-ventrally and has a correspondingly long surface of insertion on the palato-quadrate. The
ventro-lateral edge of this surface of insertion forms a long line which begins anteriorly a t the anterior
end of the mesial plate of the entopterygoid, extends the full length of the line of attachment
of th a t plate to the palatine, ectopterygoid and metapterygoid, lying in the V-shaped space between
the two limbs of the bone, and then, beyond the entopterygoid, crosses the inner surface of the
metapterygoid to the hind edge of the body of th a t bone. There it turns upward along the hind edge
of the internal one of the two membrane flanges on the hind edge of the metapterygoid, crosses onto
the inner surface of the thin web of bone th a t fills the angle between the anterior articular head and
the shank of the hyomandibular, and turning dorso-anteriorly follows the line of origin of th a t web
its full length. The muscle thus has its insertion partly on the hyomandibular, but mainly on the
palato-quadrate.
P A L A T I N E .
The palatine contains endosteal and ectosteal components, indistinguishably fused. The
endosteal component forms the thickened body of the bone, and its curved, relatively long and rodlike
anterior end. The ectosteal component is a plate-like portion which projects ventro-laterally
from the ventral edge of the endosteal component. The anterior portion of this ectosteal component
is thicker than its posterior portion, and the ventral edge of this thickened anterior portion is garnished
with small villiform teeth. The curved, anterior, rod-like portion of the bone is capped with
cartilage, articulates with the dorsal surface of the maxillary, as already fully described, and is the
maxillary process of the bone.. At the base of this maxillary process there is a small but sharp transverse
ridge, the anterior surface of which is capped with cartilage and articulates with the inferior
surface of the anterior palatine process of the ethmoid cartilage. Immediately anterior to this articular
process of the palatine, on the dorso-mesial surface of the maxillary process of the bone, a little
flattened surface gives insertion to the rostro-palatine ligament. Directly opposite this little surface,
on the dorso-lateral surface of the bone, a similarly flattened surface gives insertion to the ventro-
mesial end of the lachrymo-palatine ligament. On the mesial surface of the body of the bone, on a
ridge th a t lies immediately postero-ventral to the base of the maxillary process, the strong broad
vomero-palatine ligament has its insertion; the ligament running antero-mesially to its surface of
origin on the ventral surface of the vomer.
Posterior to the base of the maxillary process, the body of the palatine expands rapidly and
soon ends abruptly, this part of the bone being somewhat demicone-shaped, with its flat surface
presented ventro-mesiallv. Its hind end connects by synchondrosis with the anterior end of a block
of cartilage th a t corresponds to the middle cartilaginous remnant of my descriptions of the palato-
quadrate of Scomber. This cartilage falls away rapidly, posteriorly, and soon becomes a rod-like and
frequently imperfect and discontinuous piece of cartilage which extends backward from the ventrolateral
portion of the hind end of the body of the palatine. Against the flat ventro-mesial surface
of this cartilage, and against the corresponding surface of the hind end of the body of the palatine,
anterior to it, the anterior end of the entopterygoid rests.
The hind end of the body of the palatine, together with the cartilage immediately posterior
to it, forms a pronounced tranverse ridge on the dorso-lateral surface of this part of the palato-
quadrate apparatus, near its dorso-mesial edge. The dorso-anterior surface of this ridge, a surface
formed partly of bone and partly of cartilage, articulates with the articular surface at the mesial
end of the curved ventral edge of the arm of the ectethmoid. The articular ridge accordingly forms
the posterior ethmoid articular surface of the palatine. Its summit, which is wholly cartilaginous,
gives insertion to the strong ethmo-palatine ligament, which ligament is usually double and has
its origin on the posterior, orbital surface of the ectethmoid.
H Y O M A N D I B U L A R .
The hyomandibular is an irregular cross of primary bone, with the cross-piece placed obliquely
across the shank, and with the four angles between the cross-piece and the shank filled by
thin webbing laminae of what is apparently membrane bone.
The dorsal end of the shank of the cross forms the posterior articular head of the bone, this
head articulaticg with the pterotic. The cross-piece has articular heads at either end, the posterior
one articulating with the opercular, and the anterior one with the articular facet on the sphenotic
and prootic. The thin web of bone th a t fills the angle between the two cranial articular heads of the
bone is frequently perforated by a large foramen, due to the wear, against its inner surface, of that
process of the prootic th a t gives origin to certain of the levator muscles of the branchial arches. A
- relatively tall ridge of bone begins a t the point where, the cross-piece crosses the shank of the bone,
and runs downward and backward on the external surface of the shank. The dorsal end of the preopercular
fits against the hind surface of this ridge, and also against the outer surface of the hyomandibular
posterior to the ridge, the dorsal end of the preopercular projecting dorsally across the
opercular arm of the hyomandibular, and there leaving a space between itself and that bone. Through
this little space, th a t small superficial portion of the dilatator operculi muscle that arises in the
dilatator fossa passes, the remaining and larger portion of the muscle having its origin from the
preopercular and from the external surface of the hyomandibular internal to and posterior to th a t bone.
The ventro-anterior edge of the web of bone th a t fills the space between the anterior articular
arm and the shank of the hyomandibular is bound by a wide but strong band of fibrous tissue to the
dorsal portion of the internal one of the two posterior, membrane flanges of the metapterygoid.
Ventral to this latter flange, and ventral also to the related web of bone on the hyomandibular, the
ventral half of the external one of the two metapterygoid flanges abuts against and is firmly bound
by tissue to the anterior edge of the shank of the hyomandibular. At the ventral edge of this latter
flange, between the metapterygoid, the hyomandibular and the hyomandibulo-symplectic interspace
of cartilage, there is an oval space which transmits the arteria hyoidea.
The ventral end of the shank of the hyomandibular is in synchondrosis with the symplectic,
the two bones being separated by a relatively large interspace of cartilage which gives articulation,
on its postero-internal surface, to the small and rod-like interhyal. The interhyal lies, in its position
of rest, in the line produced of the shank of the hyomandibular; lying internal to the preopercular
and interopercular, and being bound by fibrous tissues to both those bones, the attachment to the
interopercular being particularly strong.
The facialis canal through the hyomandibular enters the bone by a large pit-like opening
on its internal surface, this opening lying in the endosteal part of the bone, close to. the angle between
the anterior articular arm and the shank of the bone. From this pit two canals arise. One runs
downward in the shank of the bone, opens on its outer surface, anterior to the ridge that gives support
to the preopercular, and transmits the truncus hyoideo-mandibularis facialis. The other runs
downward and backward and separates into two parts, one of which opens on the outer surface of