42 
MR. W. K. PARKER ON THE STRUCTURE AND 
be seen in this view, for they converge in a very curious manner to form the fore end 
of the hard palate. 
This fore part of the hard palate is semi-oval, and forms the beginning of the very 
elegant palatal roof which, altogether, would be a long ellipse if the pterygoids had 
closed in instead of keeping at the sides. The toothless dentary margin is curiously 
drawn inwards ; and the higher palatal tract of each bone is concave, and has a large 
semicircular notch where it should meet its fellow; thus the even suture is cut 
into two short tracts. The suture between these bones and the maxillaries is sinuous, 
the latter pushing forwards externally and in the middle. 
In the subcircular space between the premaxillaries the front paired vomers ( v'.) 
are seen : they are convexo-concave styles as in Tatusia. 
The broad hard palate (mx.) with its convex sides and teeth running up to the pre¬ 
maxillaries, and back beyond the palatine suture, is much more normal than what we 
see in Tatusia, and the alveolar region is thicker. The teeth, six on each side, are still 
in one groove, and they give it a moniliform appearance. Inside this arcuate cavity the 
bone is thick and cross-grooved by the palatal skin; a row of holes, instead of a 
chink or fissure, separates the sides from the inner higher part of the hard palate. 
The great pinching-in of the fore part of the bone seen in the nine-banded kinds is 
not seen here, yet the infraorbital foramen (V 2 .) is inferior, not lateral; its floor is 
much larger. 
The jugal process instead of going beyond the alveolar region does not reach so far, 
and is smaller. The palatal region of the palatine bone (pa.), instead of being very 
unlike that of the maxillaries, is very much like that tract. The two bones have a 
V\/-shaped hind margin, in front of which the bones are thick and rough as at the 
sides, just contrary to what the other kinds show; the palatines are widest where the 
pterygoid bones fit on to them ; these latter bones ( pg .) fit obliquely to the outer half 
of the palatine edge, leaving its median notch free ; they then run outwards and 
forwards. 
They have a thick, ascending, or cranial part, and a retral inferior hamular process, 
which has a concave outer and a convex inner margin, and a slight inclination to the mid¬ 
line. Each bone is tipped with true cartilage as in the Hedgehog and Mole (as I shall 
show in my next part). Yet, notwithstanding the merely lateral position of the ptery¬ 
goids, the hard palate hides the presphenoidal cartilage, which it does not in a Tatusia 
of the same age (Plate 6, fig. 1), and this great bony floor occupies the foremost two-thirds 
of the basal part of the skull. The jugals (j .) are altogether larger than in the other 
genus, and they are much further apart, through the width of the skull. The squamosal 
( sq .) carries a much larger glenoidal cartilage ( gl.f ), and it lies at the beginning of the 
hindmost fourth, instead of the hindmost third of the skull’s length. Also the annulus 
tympanicus (a.ty.) does not cover, in this aspect, the inner part of the squamosal, as in 
Tatusia; in this type that part is very large. Behind the condyloid lunule the bone 
forms a thick obtuse process with a pneumatic foramen in its postglenoid process. 
