PROZEUOLOUON. 
247 
forming the anterior portion of the narrow skull-roof between the temporal fossae, 
though the sagittal crest is not actually continued on to them. In front of this 
they widen out suddenly to form the very broad and massive supraorbital processes, 
which completely overhang the orbits, the skull-roof at this point being very wide 
and gently convex from side to side. The posterior border of each supraorbital 
process is concave and its outer end text-fig. 80) is greatly thickened and 
turned sharply down at right angles to the roof. In front of the orbit also the frontals 
are thickened and there join a pair of small bones, the lachrymals {la.), which are 
wedged in between them and the anterior end of the jugal [ju-). In the middle line 
in front the combined frontals send forwards a wedge-shaped process between the 
hinder ends of the nasals; to the side of this they are overlapped, first by the hinder 
end of the nasals, and external to these by the maxillae, the line of junction running 
outwards and forwards. The nasals {na.) are of moderate length ; posteriorly, as just 
mentioned, they are separated for a short distance by the frontals ; in front they meet 
one another in a median suture. They seem to have been about the same width 
throughout, but anteriorly they are overlapped to some extent by the facial processes of 
the premaxillae. Their anterior border in the skull described is incomplete, but it can 
be seen that they formed the posterior border of the narial opening {nar.), which they 
overhung to some extent. The rest of the border of the external nares is formed by 
the large premaxillde [pmx.]. These are greatly enlarged anteriorly, and are strongly 
convex on their outer face ; the alveolar border bears the three alveoli of the large 
incisors, the first being at the extreme end of the snout, while the others are separated 
from it and from one another by intervals of about I '5 cm.: on the outer surface 
behind and above the second aud third alveoli are slight depressions for the reception 
of the points of the lower teeth. Within the alveolar border is a rounded ridge, wbich 
is continued back on the maxilla ; there was a short palatine process. The posterior 
part of the upper surface of the combined premaxillae is gently concave from side 
to side, and forms the floor of the narial opening, which is not shar})ly defined in 
front. Posteriorly the bones send back long facial processes, which are lodged in a 
groove on the upper anterior borders of the maxilloe and form the lateral borders 
of the narial opening, deepening considerably posteriorly where they join the nasals ; 
the facial processes extend back to the level of the interval between the second 
and third premolars. 
The maxillw {mx.) are very large bones : by their upper border they unite with the 
pi'emaxillse in front, receiving the facial processes of those bones in a deep groove 
along them upper edge; behind this they join the nasals. Their posterior edge 
overlaps the anterior border of the frontals, to the outer side of which they join first 
the small lachrymals, then the anterior end of the jugals, beneath which, moreover, they 
send back a short process which bears the alveoli of the posterior molars. There is 
a large antorbital foramen {ao.f.) opening on to the side of the face at the level of the 
