462 
MR. W. K. PARKER OK THE DEVELOPMENT 
bony tracts ( p.ob.) are seen, right and left above, enclosing the olfactory nerve (I.). 
Here the cartilage (i.tr.) is alate, each sharp wing being nearer the base than the top. 
Section 3.—In this (Plate 33, fig. 3) the parts to be described are numerous, for the 
cornua trabeculae ( c.tr.) are cut through, and also the palato-quadrate (p.pg.) near its 
fore end. The intertrabecula (i.tr.) is oval in section, but it grows out, right and left, 
into wings, which thicken towards their outer edge and are as wide as the median bar ; 
these are the cornua trabeculae (c.tr.). Under their rounded end we see a small oval 
section of cartilage placed obliquely; this is the palato-quadrate ( p.pg .). The fossa 
over each cornu trabeculae is more scooped than that beneath it; in this lies the 
olfactory nerve (I.). 
Beneath the intertrabecula, and following its curve, there is a thin lamina of bone; 
this is the parasphenoid ; the oblique laminae right and left of this are the vomers. 
The palatines (pa.) are seen in the submarginal ridge, and one of the maxillary 
chain of bones (mx.) in the lesser, outer ridge. Above, some of the superior (or 
ethmo-nasal, et.n.) and supero-lateral (or preorbital, p.ob.) scutes are cut through; the 
former protect the olfactory nerves (I.). 
Part of this section (fig. 3a) is separate from the rest; it is through the lower jaw, 
in front of the tongue. 
Here Meckel’s cartilage (mk.) has a short oval section ; outside it we see the 
dentary (d.) as a larger and a lesser lamina. 
Section 4.—This (Plate 33, fig. 4) is behind the angle of the mouth, and close in 
front of the cranial cavity, where the three bars (i.tr., c.tr.) are thickest. The middle 
part is one-half higher than in the last section, and is broader above and below. The 
side bars (c.tr.) are twice as thick here, and are shorter, and upturned; the olfactory 
nerve (I.) grooves both the bars, and is more than half enclosed in cartilage. Under 
these thick rounded wings each palato-quadrate (p.pg.) is seen; it is twice as thick 
as in the last section, is circular, and is its own width below the trabecular cornu. 
As this is close behind the gape the mandible is in two sections ; the upper is small— 
it is the fore end of the coronoid process; at a good distance below this part the main 
rod (mk) is severed ; it is oval, with the narrow end above. Bony laminae belonging 
to the preorbital series of scutes are seen supero-laterahy; below the intertrabeculae 
the parasphenoid (pa.s.) is shown; a hooked, zigzag line of bone is seen propping up 
the palato-quadrate cartilage ; this is the pterygoid, whilst outside the mandible the 
dentary (d.) is visible. 
Section 5.—This (Plate 33, fig. 5) was made through the fore part of the hemi¬ 
spheres (C la .) and of the tegmen cranii. The base is formed almost entirely by the 
trabeculae (tr.) for the middle bar dies out in this region ; here they are at their 
thickest part ; they form a crescentic mass, the horns of which grow upwards and 
a little outwards as the lateral ethmoidal wall. These walls pass above into the 
convex roof; there is a superorbital enlargement where these thickish laminae pass 
into each other. 
