DEVELOPMENT OF THE SKULL IN THE CROCODILIA. 269 
thirds the length in the first stage (fig. 2), and it will be relatively much shorter than 
now. Although it appears to be straight in this aspect, it is really bent forwards near 
the end, and hooked downwards at the end (figs. 7, 8, nc), where it is slightly bulbous. 
This is like what I found in the same stage in Chelone viridis (op. cit. pl. 2. fig. 4). 
The parachordal cartilage grows up into the recess under the mid brain (C’) much 
further than the notochord, so that, already, that rod has retreated from its first position 
between the moieties of the investing mesoblast; the ascending plate of cartilage is the 
“ posterior clinoid wall” (p.cl.),a part,which is developed much more in the Sauropsida 
than in the Ichthyopsida. 
The folding over of the notochord at its end is the counterpart, in the skeleton, of 
the folding over of the mid brain; both the fore skull and the fore brain appear to be © 
outgrowths from the proper end of the skeletal and neural axes; the arrest of the 
hypoblast at this point favours such a view; this view would also put the optic and 
olfactory nerves out of the normal category’. 
The parachordal plate, which is still distinct from the auditory capsules, has very 
sinuous outlines, for it is pinched in by the pressure of those capsules and by the 
cranial nerves. 
Behind (Pl. LXIII. figs. 4, 6, oc.c, iv) the occipital condyles are being formed, and 
the plate of cartilage in front of them is pierced by the hypoglossal nerves (xi), and 
notched by the glosso-pharyngeal and vagus nerves (IX, X). 
Also the growth of the cochlez (ch/) towards the mid line causes the parachordals 
to become very narrow, thence they widen out and get in front of the auditory capsules 
(au), and at this, their widest part, they are notched by the large Gasserian ganglia (v). 
As seen from below (fig. 4, 7v) these plates seem to end in the postpituitary region, 
on this lower plane; but the upper view (fig. 6) and the sections (figs. 7, 8) correct 
this view. 
The two plates ascend under the hind brain (C’) into the large space within the 
folded mid brain (C’), and grow, right and left, into large wings; these wings are the 
alisphenoids (a/.s); they grow from the “ posterior clinoid wall” (p.cl). The base of 
each wing grows round the fore edge of the hind skull, and the tip of each touches 
the hind corner of the adze-shaped orbito-sphenoid (0.s); the upper surface of these 
wings is sinuous, and fits to the swellings of the overlying membrano-cranium. 
The basal plate looks outward, right and left, at the fore end, and is notched (for the 
notochord, ne) in the middle. Between these points the trabeculz (tr) arise; they are 
yery thick, short, pointed “ horns,” curving towards each other, but kept apart in front 
by the thick intertrabecular bar (figs. 4-6, i.tr). Above (fig. 6) the trabecule lie on 
1 The reader will observe, if he compares this with former papers of mine, that my views are becoming more 
and more in harmony with those of Prof. Huxley and Mr. Balfour. The truth of the matter is this, that I 
am gradually placing my work on an accurate embryological basis. 
