424 
MR. W. K. PARKER ON THE SKELETON 
1 and 5, tr.), for the basi-cranial fontanelle ( b.cf ) is bounded by a thick cartilage, 
which thins out in the orbito-splienoidal and ethmoidal regions (eth., o.s.) — post- 
transformcition structui-es. The floor in front of the basi-cranial fontanelle is due 
to the hind intertrabecula ( p.i.tr .). A large round notch separates the ethmoidal and 
orbito-sphenoidal regions ; the ethmoidal plate in front of this notch and of the 
thick-ribbed primary trabeculae, is a two-winged structure, pointed in the middle, 
gently concave right and left, convex above, and concave below. It thickens 
beneath at its fore margin. There is a curious rudiment of the wall and roof, right 
and left; the base of the orbito-sphenoidal wall (o.s.) is only half the breadth of 
the optic fenestra (fig.-3, II.). The top of the wall is spiked in front, and then notched 
and sinuous ; it bends inwards over the optic fenestra, and is thick above. The 
appearance, from above (Plate 19, fig. l) of these partial walls, is like that of the 
pterygo-palatines ( pg ., pa.) outside, but much smaller. The optic fenestra is kidney¬ 
shaped, the hilus being above, and the nerve (II.) passes out at the hinder third. 
The base of the alisphenoidal band (fig. 3, al.s.) is only half as large as the orbito- 
sphenoidal (o.s.), and a large uncinate foramen for the 5th and 7th nerve (V., VII.) 
intervenes between that band and the auditory capsule. Then the cartilage mounts 
over the skull cavity beyond the middle of the auditory capsules, forming a leafy 
blade, that grows, by its fore corner, towards its fellow of the other side, but does 
not meet it by a considerable space. The hind corner lies on the capsule, furthest 
from the mid-line, and a fenestra is seen between the foramen ovale (fig. 3, V.), the 
ear capsule, and the hind margin of the rudimentary “tegmen” (t.cr.). 
The front outgrowth of the cranium—the great leafy hollow cornu trabeculae 
(c.tr.) —-is more than two-thirds the size of the rest of the cranio-facial structure; 
it is emarginate at both ends, and at its hinder part it is joined on to the ethmoid 
(eth.) by a very definite tract of soft cartilage; at that part it is slightly grooved, 
above. 
At the junction of the pro- and para -chordals (tr., iv.), and also at the outer margin 
of the ethmoid, a stout band of cartilage passes out; these are united outside, as a sort 
of “ flying buttress,” which sends forwards a free snag, and downwards, at a somewhat 
greater distance from the skull, a band of cartilage, equal to the size of the root; 
this is drawn as cut across at a little distance from its origin. The hind root 
is the pedicle ( pd.) ; the front root the ethmo-palatine (e pa.) ; the spur is the pre¬ 
palatine (pr.pa.) ; the bar cut across is the epi-hyal (e.hy ), with no distinct inter- 
hyal tract; and the main outer wing is the post-palatine (pt.pa.), passing into the 
pterygoid (pg.) There is the merest convexity at the junction of the two last- 
mentioned regions, where the quadrate region and condyle should be. 
I have not figured the nasal capsule in this stage; the auditory (au.) is large, sub- 
reniform, and has a large pyriform meatus internus (fig. 3, A HI.), with the fundus 
below. 
