38 
MR. W. K. PARKER ON THE STRUCTURE AND 
in the outline of the top of the skull, a small neck to a large flask ; they are half 
the length and one-fourth the greatest width of the frontals. These latter bones 
swell over the huge turbinals, and are elegantly concave at the middle of the orbit. 
The parietals are about the size, now, of the hinder, dilated two-thirds of the frontals. 
The side view (Plate 6, fig. 3) displays many parts, and corrects the visual 
appearance of the other aspects. 
There is considerable deflexion of the snout, the nasals reach nearly to the end, 
above, and the nostrils look downwards. 
The premaxillaries now form a squarish tract, followed by the maxillaries which 
overlap them ; these latter bones are half as long as the skull, they rise high, 
midway between the orbit and the end of the snout, have their infraorbital foramen 
(V 2 .) very low, and their jugal process notched to let in the jugal. The large 
lacrymal (/.) has a roughly triangular outline, externally, the orbital margin, where it 
has its hole (l.c.), and its antorbital flange, is concave. It covers in the upper turbinal 
region, which was exposed in the second stage (Plate 2, fig. 8); its upper suture, with 
the frontal, and its lower, with the maxillary, are nearly equal ; both of those margins 
of the lacrymal are gently convex. The frontal (f) swells over the lacrymal; it is 
then somewhat notched where it runs inwards as the orbital plate, which hides nearly 
all the orhitosphenoid ; the whole bone is rounded where the roof passes into the 
orbital wall. 
The large rounded parietal (p.) helps but little towards forming the temporal fossa; 
it has a slight concavity, besides, near its hind border, where it just overlaps the supra - 
occipital ( s.o .). From that part, behind, but not quite so far back, the squamosal (sq.) 
reaches to the orbitosphenoid in front. Its three regions, the post-temporal, post- 
orbital, and jugal are all nearly of equal length ; the last of these is stout, and the 
pre- and postglenoid processes are well marked, the latter being the larger of the two. 
In the postorbital region it forms a large triradiate suture with the frontal and 
parietal; these bones so united do nothing towards enclosing the orbital space, which 
is only marked out well in its antero-inferior half. Part .of the palatine, pterygoid, 
and alisphenoid can be seen in this view, and also the annulus ( a.ty .), the manubrium 
mallei ( m.ml ., line directed wrong), the epihyal ( e.hy .), the facial nerve (VII.), the 
opisthotic region and the parts of the occipital arch (s.o., e.o ., oc.c.). 
The lower jaw (figs. 3 and 3a) has retained its elegant shape; it has still some 
cartilage on its projections, especially for the condyle ( cd.jq .). The splenial and coro- 
noid regions hang well over Meckel’s cartilage ( mk .), which is still perfect. The 
malleus (figs. 3a and 6, ml.) and incus (i.) are almost ossified, and the stapes (st.) now 
a slenderer and more elegant “ stirrup,” has the lower part of its crura, and the centre 
of its base, bony. The little module of cartilage in the stapedius ( st.m .) is now a mere 
projection on the neck of the stapes. The upper ceratohyal (fig. 5, c.hy.) has a small 
ring of bone near its base; the rest of the hyoid arch is still cartilaginous, and is 
little altered since the last stage. 
