DEVELOPMENT OF THE SKULL IN THE CROCODILIA. 283 
a deep groove runs down inside between the fore edge of the capsule and the out- 
turned selvedges of the hooked, overlapping alisphenoid (a/.s). In section (Pl. LX VII. 
fig. 8) the auditory capsule is seen to be very distinct from the wide, swelling plate 
below—the double parachordal, with the uniting notochord and its ossifying sheath 
(4.0, iv, ne). 
This section is in front of the supraoccipital cartilage; it cuts through the falcate 
otic process (ot.p) of the quadrate and its lower or articular part (g); the articular part 
of the mandible (ar) is seen in situ. Fitting into the fenestra ovalis ( fs.0), the columella 
(m.st) is seen, behind it a narrow tract of cartilage is cut through, and then there is 
another opening, the fenestra rotunda (f.7). This section is through the mouth of 
the cochlea, and thus seems to show the two fenestre as opening into one cavity. The 
fore part of the sacculus (vd) is cut across above and within, and above it, in the crest 
of the capsule, the neck of the first ampulla (a.s.c). The columella has its medio- 
stapedial part (m.st) ossified, and its extrastapedial end (e.st) is seen rising outside the 
otic process of the quadrate. We must look further back for any rudiment of the 
“teomen tympani” (Pl. LXV. fig. 8); it exists here merely as the projection of the 
canals. 
The fenestre in the walls of the skull differ from those in the Bird, and are of less 
extent than those in the Lizard; in the former the alisphenoid itself is fenestrate ; 
here there is a large space between the orbito- and alisphenoids, well margined above 
by a band which is not found in the Bird; whilst a smaller band below divides that 
from another smaller fenestra between the hind part of the orbito-sphenoid and the 
presphenoid. 
As I have just shown, the alisphenoid, instead of lying far from the auditory capsule, 
as in the Lizard, clings close to it, here, and is only separated from it by a chink. The 
postsphenoidal region is cut through in another section (Pl. LXVII. fig. 7) just at the 
back of the pituitary cup (py), which is seen to have some “acini” of the “gland” 
in it. Here the ossification (d.s) has reached the cup (Pl. LXV. figs. 6,7, 6.s); but 
the part where the parachordals pass into the prochordals, laterally, is unossified ; here 
the alisphenoids (a/.s) are seen to be direct continuations of the basal (parachordal) 
plate. Above, the fenestra is cut across at its hind part, and the upper band (u.0.al) is 
strong and incurved. 
The front angle of the otic process of the quadrate (ot.p) is seen in section, outside 
and below that band. 
In the next section, through the front of the pituitary cup (Pl. LX VII. fig. 6, py), 
the apices of the trabecule (tr) are cut across, close in front of the growing basi- 
sphenoid bone (8.s). The optic nerves (11) are severed close below the lower band 
of cartilage, the lower orbito-alisphenoidal band (/.0.a/) ; and above, at some distance, 
the upper band (w.0.a/) is severed, where it is thickening towards its fore part. 
Meckel’s cartilage (mk) is seen in section also. In front of the pituitary body 
