MR. W. K. PARKER ON THE STRUCTURE AND 
cartilages (fig. 9, al.sp.) have coalesced with the ethmoidal tract ( al.e .); here the 
septum (s.n.) as it becomes “perpendicular ethmoid” (p.e.) is confluent below with the 
coalesced trabeculae (tr.). On one side the section is seen to pass into the palato- 
pterygoid band (p.p>g.). 
The 5th section (Plate 9, fig. 4), rather more than half of which is shown, is through 
the ethmoidal part of the skull proper, where the nasal cavities (n.p.) are closing in. 
The perpendicular ethmoid is seen to be very thick, and the trabecula (tr.) to pass into 
the solid root of the palato-pterygoid bar (p.pg.) from which ascends, suddenly, on 
the outside, the strong arcuate “orbitar process” of the suspensorium (or.p). 
The 6th section (Plate 3, fig. 11) is through the solid ethmoid where it closes in the 
skull, leaving only the olfactory nerve-passages (1); here the skull is as solid as that of 
a Chimcera. The palato-pterygoid bars (ppg-) are cut through, outside the “post¬ 
palatine rudiment” (see Plate 3, fig. 1, pt.pa.), whose form, as a gentle elevation, is 
there shown. 
The 7th section (Plate 3, fig. 12) is behind the palato-pterygoid, and through the 
fore part of the skull-barge , where the olfactory crura (1) are given off. The cavity is 
elliptical, the wide wall thick, the roof (anterior “ tegmen,” t.cr .) and the floor are 
gently concave. 
On the roof we see the fore end of the frontals (/■), and under the floor the 
parasphenoid ( pa.s .). 
The 8th section (Plate 3, fig. 13) is behind the “tegmen” and through the fore part 
of the “ fontanelle,” covered by the widest part of the frontals (f.) ; the bone below is 
widening, it is the parasphenoid ( pa.s.). The elliptical cavity is deeper, the walls 
thinner, and the floor is now convex. 
The concavity, below, in the two last sections, is due to the drawing in of the 
trabeculae, and the high, vertical form of the “ intertrabecular ” tract in the fore skull, 
is now a bulging' floor. 
The 9th section (Plate 9, fig. 5) is through the middle tegmen, between the great 
median and the lesser paired “ fontanelles,” and also through the widening parietals 
(f, by mistake for pi). Here the roof passes into the wall, downwards; then there 
is a large fenestra optica on each side, with the optic nerves (IP) emerging; and then 
the rounded trabeculae, with the bulging “ intertrabecular tract,” floored by the para¬ 
sphenoid (tr., pa.s.). 
The 1 0th section (Plate 9, fig. 6) is through a lateral fontanelle, the hind part 
of the parietal (p.), and the auditory capsule, confluent with the basal plate (iv.). 
The anterior and horizontal canals ( a.s.c ., h.s.c.) are cut through, and the general cavity 
of the vestibule (cm.) laid open. 
The “ tegmen tympani ” ( t.ty .) is seen projecting from the outside of the capsule, 
beyond the horizontal canal ; and the basal plate, or “investing mass,” is seen to grow 
outwards as a floor to the tympanic cavity ( ty.f.). This plate is deficient, more or less, 
behind, the capsule resting on an imperfect floor below, and projecting into a fenestra 
in the wall of the skull. 
