subsiding in front towards the maxillary, it is rounded off into the obtuse apex behind; the posterior is
shorter, subconcave, and terminates at the anterior part of the sphenoidal plate; its inner surface is concave
in the anteroposterior diameter, but subconvex vertically; a groove, corresponding to the crest externally,
indicates the junction of its concavity with that of the nasal process. The narrow, elliptical, posterior
nasal fissure is, anteriorly, prolonged into the slit between the lateral mandibular beams; in the dried state
of the soft parts, the anterior angle of the posterior nares was two inches two hues and a half anterior to
the point where the palatines meet on t he rostrum.
An oblique line, directed forwards and inwards from the convexity of the crest to its inner margin
anterior to the subsidence of the palatine process, defines the fossa between the crest and the palatine
process, which gives attachment to the fleshy fibres of the internal pterygoid; the depressed tract on
the anterior part of the crest, gives attachment to the tendon of that muscle; its fleshy fibres also arise
from the fossa between the nasal process and crest, which is concave vertically and convex horizontally;
it is prolonged posteriorly into a deep rough depression on t he outer surface of the sphenoidal plate, at the
bottom of winch is the pneumatic aperture. The palatine bone is almost destitute of pneumaticitv; the
length of its free portion is two mches and a half.
The pterygoid bone, one inch two lines and a half long, is curved like the human clavicle, convex
externally in front, and concave behind, and formed by a thin narrow band, twisted on itself and expanded
at both extremities. The outer edge is thick and rounded behind; in front it becomes thinner, being
flattened inwards, so as to encroach on t he upper aspect, which thus exhibits an elongated triangular tract
passing into the base of the inner extremity. The inner edge presents, on the left side, an angular
projection in the centre, the rudiment of the sphenoidal articular surface; anterior to which it is flattened
outwards, extending to the apex of the inner facet; the inferior surface is thus grooved in its two anterior
thirds. On the upper aspect, a bidentate crest extends from the outer extremity obliquely inwards, and
subsides towards the centre, bounding internally a lanceolate space. The inner extremity is triangular;
the surface gliding on the sphenoid is slightly convex, and its anterior edge is united by ligament to the
palatine bone; the compressed, oval posterior extremity is impressed by a narrow deep concavity for articulation
with the tympanic. The pterygoid is destitute of pneumaticity.
The tympanic bone, viewed from behind, is X shaped; the lower segment being most extended transversely.
The internal hinb above is bent backwards, and supports an oblong articular tubercle, forming
the posterior condyle, around its base are several foramina; the anterior is larger and covered by a triangular
synovial surface, the apex behind its inner angle extends into a curved linear strip connecting them;
the ligamentous groove is most distinct anteriorly and externally in both. A deep circular concavity, with
a reticulate floor pierced by numerous pneumatic apertures, separates them posteriorly. A slight ridge,
leading from the external condyle to an inflected notch at the centre of the outer concave edge, indicates
the attachment of the membrana tympani. The inner margin is more denned, less curved, and exhibits a
semi-obovate outline. Viewed externally, the figure is cruciform; the lower and outer angle projecting,
and impressed by a deep pit for the extremity of the zygoma. The orbital process, corresponding to the
upper and inner limb, is formed by a thin, curved, triangular plate; the apex is broadly truncated, inflated
and slightly deflected outwards above; the outer surface is convex and pitted for the external pterygoid
muscle, except for a narrow tract beneath the apex, extending backwards along its upper margin, which
runs outwards to the anterior condyle; its iid'erior angle is bent inwards and expanded into a narrow
pterygoid convexity, at the apex of which is a pneumatic foramen. The inferior moiety of the external
aspect is smooth, polished, and convex across the projecting angle.
The inner surface presents a tripartite fossa, deepest inferiorly, rough tliroughout; and obliterated
towards the extremity of its anterior angle by the expansion of the diploe of the orbital process, which is
subtranslucent: it gives insertion to the levator muscle. A triangular flattened surface, its base extending
between the condyles, separates the upper limb from a slight concavity, which impresses the external
surface above, and indents the orbital process.
The mandibular extremity is compressed in the anteroposterior diameter; widest externally, and
constricted in the centre. In its internal half, it forms a narrow transversely extended and downwardly
projecting crest; the outer segment is flattened vertically into a quadrate plate, and twisted from before
backwards on its axis. A broad groove directed obliquely forwards renders its inner moiety subconcave,
and hollows out t he inner tubercle externally. Articular cartilage covers the backwardly sloping inferior
surface of the outer condyle, dips into the groove, and expands over the thick rounded edge of the inner
one, which presents a large reticulated pneumatic foramen, and over its anterior surface, at the external
angle of which it is narrowest. The greatest diagonal is one inch four lines and a half, and the least one
inch three fines; the width of the upper extremity is eight lines and a half, and that of the lower one inch;
it is three lines broad where most constricted. The orbital process is seven lines long; from its apex,
which is three lines and a half wide, to the zygomatic angle, is one inch and three lines. The width of the
outer mandibular condyle is five lines, of the inner two fines and a hah"; the length of the former is four
lines; that of the latter, five lines and a half.
The rami of the lower jaw, six inches in length, measured along the lower border, are separated by an
interval of two inches seven lines between their angles, but unite at a short, acute symphysis, which ascends
at an angle of about 4 5 ° with the lower margin. Each ramus is thin aud curved, the convexity mounting,
external to the palatine wedge, into the angle between the inferior margin of the maxilla and the zygoma.
The greatest height is at the centre, and amounts to one inch; it diminishes slightly towards each extremity.
The upper edge is sigmoidal, convex behind, but concave in front; the profile line of the sharp upper edge
of the core ascending very gradually as it advances, and then curving rapidly downwards to the mesial line
of the symphysis, which is broadly emarginate anteriorly, concave above and subangularly rounded below;
its convexity is adapted to the concavity of the edge of the upper core, while the decurved apex of the latter
is fitted to its emargination. The lower concave edge is rendered slightly convex towards the centre of the
posterior moiety, by the projection downwards of the dentary and angular elements. The dentary piece,
exclusive of the core, is subequal in length to the posterior segment of the ramus; which is formed by the
coalescence of the surangular, angular, and articular elements; the opercular remains distinct, perhaps, to
a late period of life.
The dentary bifurcates posteriorly; the upper limb is slit vertically, to receive the surangular, whose
free portion, unoverlapped by the long narrow inucr dentary plate, advances halfway to the core; the
suture between it and the short deeper outer lamina, is seen along the upper edge. The lower limb extends
backwards, contracting, along the outer surface of the angular; whose tliick lower border, thinninganteriorly,
passes forwards, between it and the opercular, as far as t he centre of the inferior edge of the ramus. The
irregularly lanceolate opercular, partly covers the angtdar and dentary pieces, and rises to close the compressed
space (dental canal) containing nerves and vessels; its posterior extremity extends along the inner
surface of the angular, beneath the inflated portion of the articular; its superior border comes in contact
with the inner and upper dentary lamina; anteriorly it terminates one inch behind the lower angle of
the symphysis, its inferior edge diverging from that of the dentary; its length is about three inches, and
its greatest depth six lines. The opercular begins to coalesce with the dentary, along the anterior part of
2 c