168 
MR. W. K. PARKER OK THE STRUCTURE AUD 
The moutli is nearly closed, the upper and lower lips, as in the next section (u.1., l.l.), 
are seen with their rugae, but without their teeth, and in the lower lip the mandibles 
(rah.) are just brought into view. 
The parietal scutes were cut through above, and post- and sub-orbitals were seen, at 
the sides, and below, but not figured. 
Section 11.—In this section (Plate 17, fig. 3) the sphenotic lamina (sp.o.) is thicker, 
but is still separated by a notch from the tegmen cranii ( t.cr .); that part is thinner in 
the middle, and deeply concave. Here the cranial cavity has widened, for the section 
is close in front of the mid-brain. The section, now, is that of an Ox face with 
drooping horns, and the muzzle is now narrower around and under the infundibulum 
(inf.). On account of the very small size of the eye-ball (Plate 17, fig. 1, e.) four of 
these sections are between the eye and the ear; in this the orbital wall (o.s.), which is 
extremely thick, is twice scooped for the orbital muscles and the fatty masses that 
occupy the orbit—much too large for the eye-ball. Here the intertrabecula has died 
out, and the trabeculae (tr.) have united directly with each other, and the plate thus 
formed has lost half the thickness seen in the last section (Plate 17, fig. 2, tr., i.tr.). 
The primary form of the trabeculae is still seen at the sides, below, and the whole 
of the basal plate is crenate, making the parasphenoid (pa.s.) assume an undulated 
form as it follows the risings and fallings of the cartilage. In this section the oral 
apparatus is cut through the middle, and the opening itself is crescentic below, with 
a notched upper outline ; this is due to the projection right and left of the pterygo- 
quadrates (pg.q.) and their investing bones, the palatines (pa.,pg.). 
Here, the cartilages covered by the large adductor muscles (acl.m.) are sigmoid in 
section, and besides the outer bones, the pterygoids (pg.) now show themselves, both 
as an inner and an outer section, being through their forks. The quadrate region, with 
its orbitar process (q., or.p.) is separate, now, and over it is the maxillary (mx.) ; to 
the quadrate the mandible (rah.) is.articulated, it then passes almost directly inwards 
towards its fellow, which it does not quite meet; the dentary (d.) is seen flanking the 
Meckelian rod. 
Section 12.—In this section (Plate 17, fig. 4) the cranial cavity is Y-shaped, and 
contains the front of the mid-brain above the fore-brain (C 1 .), with the infundibulum 
passing into the pituitary body (py). Here, in front of the post-clinoid wall, the 
alisphenoidal region (al,s.) is extremely thick —twice as thick as the tegmen (t.cr.) and 
the continuous sphenotic wings (sp.o.). 
In this section the parts round the mouth are like those of the last, but the 
foremost azygous metapterygoid (mt.pf.) comes into view, and the mandibles {rah.) are 
cut away, distally. 
Section 13.—This (Plate 17, fig. 5) is through the middle of the mid-brain (C 2 .), 
- and the back of the pituitary body (pry.). The post-clinoid wall, which is an oblique 
shelf running forwards and a little upwards (Plate 16, fig. 2, p.cl.), is here cut through 
obliquely so as to appear thicker than it is actually. This section seems to show 
