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PROFESSOR H. G. SEELEY OR THE STRUCTURE, ORGARIZATIOR, 
in contact, but merge in the median mass of the pterygoid, which is 3 centims, deep 
and 1'7 centim. wide, with convex sides, but vertically compressed to a sharp palatal 
ridge and a similar median ridge on its upper surface. The mass is fractured 
vertically in front, but shows no trace of a median suture (fig. 1). The median blunt 
longitudinal pterygoid keel distinguishes this species from all others, and nothing 
could be less like the expanded horizontal plates which the pterygoid bones form 
in other Anomodonts. 
The squamosal bones appear to have a considerable lateral extension forward in the 
upper part of the wall of the temporal region in advance of the origin of the zygomatic 
process. The antero-posterior measurement, as preserved, from the middle of the 
convex posterior border is 10 centims. The zygomatic process, which is directed at 
first obliquely outward, and then parallel to the temporal region of the skull, is given 
olf in the middle of the width of the bone by a vertical attachment 5 centims. high and 
fully a centimetre wide, which becomes narrower superiorly as the zygomatic process 
thins. Beneath this branch the lateral contour of the bone is convex vertically for 
3^ centims. down to the quadrate bone (fig. 2); and this convexity with the superior 
process defines the posterior vertical concavity in the bone, which increases in depth 
superiorly as this part of the bone becomes narrower. Interiorly the concavity is lost. 
At the articulation for the lower jaw the squamosal bone appears to form the entire 
height of the back of the skull, which is about 12 centims. ; but distally, where it rests 
upon the quadrate, it contracts to a width of 1'7 centim., and both the anterior and 
posterior borders of the descending process are concave for a length of about 3 centims. 
At I centim. from the distal end there is a transverse suture, and an ossification is 
displaced, which is 1 centim. deep, 2A centims. from back to front, and over a centi¬ 
metre from within outward. Its distal surface appears to have been articular, and is 
convex from within outward and gently convex from front to back, as though it 
formed the outer half of the condylar articulation for the lower jaw. There is a 
similar transverse division on the left side, where the ossification is w situ, but the 
outer part of both bones is there broken away. In its relations to the quadrate and 
squamosal this ossification, if its distinctness is established, would correspond to the 
quadrato-jugal bone, which is not otherwise seen in Anomodonts. 
The part of the squamosal bone which is anterior to the zygomatic process is about 
4 centims. deep posteriorly, is sub-triangular, contracts in depth anteriorly. The post- 
parietal bones rest upon it superiorly, and it is in contact with other bones in front 
which converge forward and form the vertical median post-orbital plate. In front of 
the delicate process which extends above the superior border of the quadrate is a 
foramen from which a concave channel extends obliquely upward, over a sub-quadrate 
bone 3 centims. high and as wide, which lies in the wall of the brain case, widening it 
transversely above the quadrate process of the pterygoid, which is itself in close 
contact with the basi-sphenoid bone ; So that its position is that of the ali-sphenoid 
bone, or pro-otic, and it may be compared with the thickened plate which flanks the 
