136 
MR. W. K. PARKER ON THE STRUCTURE AND 
basisphenoidal cartilage ( b.s .) has a film of bone in it above and below ; its outer edges 
are beginning to coalesce with the cochlea, which are laid open. The orbitospbenoidal 
band (o.s'.) is still large, and is separated by a large space from the inferolateral parts. 
The processus gracilis has still a solid cartilage lying on it (ml.) ; outside this is 
the postglenoid part of the squamosal. The meatus auditorius externus is partly 
laid open, and the Eustachian cartilage ( m.c .) is still seen under the cavum 
tympani (c.ty.), which is here still partly the Eustachian tube. Beneath the 
middle of these parts the epihyal ( e.hy .) is cut across, and outside it the chorda 
tympani (VIE.), with the main facial nerve (VII.) lower down, is exposed. The 
larynx is below the pharynx (lx., phx.), and there is seen a film of bone outside, 
the ramus (d.) ; a part of the cartilaginous framework of the larynx is seen in section. 
1 7th Section (Plate 18, fig. 17). —This is another important slice, showing many 
things. It is in front of the junction of the orbitosphenoid with the crest on 
the top of the auditory capsule ; the cochlea (chi.) is near its widest part, it is just 
in front of the proximate coil. We are now behind the great trigeminal nerve, with 
its roots, ganglion, and branches, but the nerves proceeding from the ganglion geni- 
culatum (VII., VIII.) are cut across, and the facial nerve (VII.) has entered its 
“ aqueductus.” The same nerve (VII.), and its inosculating anterior branch, the 
chorda tympani, are seen outside the epihyal (e.hy. VII.).* Here the great meatus 
externus (m.a.e.) is fairly laid open, and it is seen to be lined with cartilage 
throughout; it is indeed one more or less segmented tube, from the opening of 
the Eustachian tube, within, to the conchal expansion, without. The pituitary 
body (py.) is cut through in its hind part; the malleus, or dilated end of Meckel’s 
cartilage (ml.), is partly seen, its head and the tip of the manubrium (mb.) ; the 
rest of that process is indicated on the right side by a dotted line. The archway 
over the facial nerve (VII.) is the fore part of the tegmen tympani, inside the head 
of the malleus. The postglenoid part of the squamosal is seen, and on right and left 
of the pharynx (phx.) the hypohyals (h.hy.). 
18 th Section (Plate 18, fig. 18). —This section is through the basis cranii where 
the sphenoidal (b.s.) and occipital regions meet. The orbitosphenoidal cartilage has 
here passed into the supra-auditory (s.a.c.), where this great crest is continuous with 
the top of the auditory capsule. The left side of the figure is from a point in 
front of the right, so that this section serves instead of two. The left side is 
through the base of the cochlea (chi.), but in front of the cavity of the vestibule. 
The cartilage lining the meatus externus (m.c.) is seen both in the outer opening and 
under the dagger-shaped section of the cavum tympani (c.ty.); a small cavity at 
present lying in the midst of a mass of indifferent tissue. The solid cartilage of the 
“ pterotic ” region, close in front of the anterior semicircular canal (see the other 
side ci.s.c.), is not perforated until we come to the beginning of the aqueductus for 
the facial nerve (VII.), which is cut across twice on the right side, both where it 
* The lines are misdirected in this part of the figure. 
