DEVELOPMENT OF THE SKULL IN THE PIG. 
301 
(c.hy.) is cut through near its junction with the long stylohyal, and the “ cornu major ” 
(br. 1) is shown in its whole extent on each side; whilst between w r e have the basal 
piece ( b.br .), not, truly, a basihyal, but answering to the first basibranchial of the Fish. 
The larynx (lx.) is below and behind them, and behind it is the oesophagus (os.). 
Another section (Plate XXX. fig. 3), taken further back than the last, shows the sphe- 
noidal, auditory, and occipital regions as seen from above. The differentiation of parts 
has gone on very rapidly, whilst the embryo has merely become longer by one half, and 
the difficulties in the way of interpretation are largely removed. 
In front the “ anterior clinoid wall ” (a.cl.) is seen to be symmetrically divided at the 
mid line ; this is the junction of the trabeculee at the end of their long commissure, in 
front of the outbent blades which pass around the pituitary region. The pituitary cup 
is deep, wide, narrow above, and has a crescentic form, the concavity of which looks 
forwards. Be.tween this actual cavity and the free ascending ends of the notochord and 
investing mass there is a large amount of gelatinous tissue, through which the wavy 
internal carotids (i.c.) pass, converging and again diverging. The gelatinous tract, the 
base of the so-called “ middle trabecula ” (see Plate XXVIII. fig. 6, m.tr.), is widest close 
to the ear-sacs, and narrows to the edge of the pituitary pit ; on each side of it is seen 
a bulbous mass, the Gasserian ganglion (5). On each side of the extremity of the 
notochord and investing mass are seen the well-defined ear-sacs, which are here cut 
through in their cochlear region ; the coils are now well developed. On the left side 
the section is behind and below that shown on the right, where the “ malleus ” or head 
of the first postoral is cut through, the shaft of the second arch, and the “ meatus 
externus ” and outer ear. Part of a similar section, taken lower down (fig. 4), displays 
the orbito-sphenoids in section (with their upper part cut away) ; and where they have 
coalesced with the trabecular commissure, there the optic nerves (2) are crossing. The 
alisphenoids (al.s.) are sections seen in their whole extent, but not their connexion 
with the basisphenoid, the notochordal region of which is displayed, backwards to 
where the basioccipital territory begins. 
At a lower level closely packed cells are developing into cartilage, which will form 
a secondary floor to the pituitary body, the seat of the “ sella turcica;” then the poste- 
rior sphenoid will be morphologically complete. The connexion of the two great post- 
oral bars with the auditory capsule will be better understood by two more sectional 
views similar to the large figure (Plate XXX. fig. 3), but of more limited extent and 
more highly magnified : all these figures are made from the antero-inferior aspect of the 
up-tilted basis cranii, the sections, which in the nasal region were vertical ( figs. 1 & 2), 
being horizontal behind. Such a section (Plate XXX. fig. 5) through the outer ear or 
concha (ca.) and head of the first postoral bar shows how curiously incurved this capitular 
portion is, and how that its apex is developed into an orbicular part, like that on the 
apex of the next bar. The shoulder, which articulates with the upper part of the 
next bar, is very bulbous, and at the root of the neck a conical boss is sent outward ; 
the shoulder is the head of the malleus, the boss is the process for attachment of the 
