174 PROF. W. K. PARKER ON THE STRUCTURE AND 
fourth as large as the maxillaries, which yet only reach halfway to the hinge of the 
lower jaw. 
The nasal processes of the premaxillaries (n. pa) are sharp wedges let into the upper 
part of the nasals; they articulate one with the other by sharp teeth, and they are 
hollowed out above. At their sharp ends they diverge; and here the middle nasal 
passage can be seen, bounded behind by the nasals. 
The whole palatal dentigerous part (Pl. XX XVII. fig. 1, px, mx) forms rather more 
than the third of a large circle, and is only divided by the median suture. The ranks 
of long pupiform teeth stand against the sharp dentary edge of the bones which grow 
into the palatal region to an equal extent beyond the tooth-bearing part. 
Each maxillary (m2) is a thick rib-like bone, its notched ascending plate being the 
“head ;” the outer surface is convex, pitted, punctured, and more or less irregularly 
mamillate. ‘The free jugal part enlarges, and then has a rounded and bevelled end. 
Below (Pl. XX XVII. fig. 1), the concave edge of the great dentigerous arc is fitted 
with a similar structure, which, however, is only one third the extent of the outer part ; 
this is also divided at the mid line; it is composed of the vomers and palatines (v, pa), 
which also are ankylosed together. 
Together these bones present a thick convexo-concave dentary edge in front, in the 
concave part of which the ranks of straight teeth stand. Then these smooth denti- 
gerous wings give off each a subtriangular plate, joined to its fellow by a harmony- 
suture. These gently lessening plates have a rounded notch at their margin where they 
come off from the wings, and then grow backwards beneath the great parasphenoidal 
floor (the /eft being larger than the right), and end as sharpish wedges. The outer 
two thirds of the dentigerous wings belong to the palatines (pa); these bones pass to 
the hinder flat part for a short distance ; but the main part of the smooth plates belong 
to the vomers (v). 
The parasphenoid ( pa.s) forms a floor to all but the outer edges of the endocranium ; 
it is wide behind, growing out in toothed processes in the basitemporal region, but 
narrower forward where it passes over the hinder angles of the vomers. 
There it is thin, and is grooved or scored both in straight lines and obliquely ; along 
its middle third it articulates, by an irregular suture, with the inner edge of the 
pterygoid. 
It is not distinguishable from the hinder half of the occipital cincture, under the 
foramen magnum, and evidently has yielded much of the bony matter that forms the 
cochleate median process that underlies the concave facet for the odontoid rudiment; 
further forwards the parasphenoid is free ; it is flat in front and convex behind. 
The dentary (Pl. XXXVI. figs. 2 & 3, d) is a long, large, thick bone, which gives 
the outline to all but the condyle and angle of the mandibular ramus; it rises into a 
small coronoid process under the end of the maxillary, sends up’an outer alveolar wall 
for the outer rows of teeth, and grows inwards below (fig. 3) to form the edge of 
