DEVELOPMENT OF THE SKULL IN THE MAMMALIA. 95 
Insectivores, where this floor fills in well, at first, and then suffers large absorption in 
the part where the maxillaries and palatines join. If we compare this with the two 
previous stages, and with the adult, we shall see that there is a steady attempt to pass 
from the normal primary schizognathous condition to the normal secondary desmog- 
nathous state, and that in this curious toothless type the latter is never attained to— 
it comes short of the mark of the high and perfect Mammalian hard palate.* 
Only in the hinder third do the concave palatine plates of the maxillaries approxi- 
mate, and then not perfectly ; in the front third they fail to hide the palatine spikes 
of the premaxillaries which run, as a wedge, far into the angle formed by those bones. 
In the middle third they are divided by the protruding ridge on the fore part of the 
vomer. The scooped part of the maxillaries inside the sharp alveolar edge is twice 
as large as the second and still more scooped part near the mid-line; where the bones 
nearly meet behind their thin edge is thickened. That thickened edge ends in a 
point, and the corresponding palatine sends its pointed fore end between that point 
and the outer flange of the bone which runs backwards and outwards. The outline of 
the maxillary is then notched, then bulbous, and is then obliquely cut away, where 
it articulates with the frontal ; the infraorbital foramen (V*.) has but a small bridge 
under it, but from it there runs a considerable fossa upwards and forwards. Behind 
the bridge the jugal process is very stunted. 
On each side of the vomer, the maxillaries are most concave; that bone (v.) is thick 
and split at its fore end. This exposed part is of great interest to the morphologist ; 
it corresponds with the enlarged dentigerous fore end of the bone in osseous Fishes, 
which in their extreme specialization have acquired a median vomer; and also with 
the flat infero-anterior part of the vomer of the Green Turtle (Chelone viridis) (« Chal- 
lenger Series,’ vol. 1, Zool., plates 10 and 11); and of certain Birds, e.g., Fulco, Dicho- 
lophus (Trans. Linn. Soe., ser. 2, Zool., vol. i., plate 24). Odd enough, one of the 
strongest and most perfectly specialized of the skulls of the Eutheria—that of the 
Cat—shows a trace of this very plate, where the maxillaries fail to meet in the hard 
palate. 
The palatines (pa.) form a squarish tract ; they make about one-third of the hard 
palate, which ends with them; and, indeed, they fail to produce the plate in their 
hinder fourth, and the hind margin of the hard palate is cut away in a crescentic 
manner. The submarginal groove of the maxillary palatine plate runs on under the 
palatine, but soon turns outwards and is lost. The palatines form one-third of the 
wall of the great nasopalatine canal behind, and the pterygoids (pg.) two-thirds ; these 
bones, like the palatines, have a broad basicranial flange, and this upper dilatation of 
these vertical bones overlaps the basioccipital. The wall or vertical part is deeply 
notched behind, and thus the hamular process (see also fig. 8, pg.) is large and free. 
* To me this seems to suggest that whilst the Pangolin has suffered degeneration and relapse, as 
it were, as rezards the teeth, and with the teeth the size and fulness of the jaws, yet that this abor- 
tion and suppression began when the type itself was very low, and only very imperfectly desmognathous. 
