SKELETON OF PHORORHACOS INFLATUS. 61 
possible to make out the extent and relations of the facial parts of the maxill, and it 
is therefore uncertain what share, if any, they may take in forming the boundary of 
the nostrils. 
The premazille no doubt form the greater part of the enormous beak, but their 
exact boundaries are not distinct. Superiorly they send out fused nasal processes, which 
form at least the upper part of the high bar of bone between the nostrils and perhaps 
extended to the frontals. Anteriorly the bodies of the premaxillz form the high laterally- 
compressed anterior section of the beak, the tip of which forms a downwardly-directed 
hook, about 3°5 cm. long and small compared to the bulk of the whole beak. From 
the sides of the base of this hook a pair of parallel ridges run back on to the palate ; 
their posterior portion is separated from the tomium by a deep groove, into which the 
edge of the mandible fits when closed ; on their inner side also there is a deep channel, 
divided by a median ridge, which just behind the decurved hook rises into a prominent 
tuberosity, at first described as a tooth. 
The cutting-edge of the beak forms a double curve; it commence a little behind the 
point and first forms a strongly convex, prominent edge, sharp in front, but more 
rounded behind ; posteriorly it is very slightly concave, and is a continuation of the 
line of the lower edge of the jugal arch. The anterior convex portion is no doubt 
formed by the premaxille ; the posterior is maxillary. In the premaxillary region the 
narrow palate is closed, except for a few smail median foramina, and is deeply 
concave from side to side. 
The beak, as a whole, is very deep from above downward, strongly compressed 
laterally, and its whole surface covered with angular and vascular impressions, which 
indicate that in life it was covered with a very thick horny sheath ; the whole must have 
formed an extremely formidable weapon, whether for attack or defeuce. 
The upper portion of the cranial region of the skull is much flattened (Plate XV. 
fig. 2). Posteriorly it is greatly constricted by the great temporal fosse, which are 
separated in the middle line by an interval of about 12 mm. only. In front of these 
it widens out and reaches its greatest width at the level of the postorbital processes. 
In front of these it again narrows, and anteriorly the frontals join the nasals, but their 
limits are not very clear. he orbital borders of the frontals have thick roughened 
edges, and probably the great supraorbital plates of the lachrymals, which now lie 
slightly below the level of the frontals, may, in their normal condition, have united 
with them throughout their whole extent; but, since their position is symmetrical 
on the two sides, it is possible they may be in their natural position. As already 
mentioned, this depression of the suprasrbital plates gives the skull, when looked at 
from above, the appearance of having possessed deep supraorbital fossa. 
The Palate (Plate XV. fig. 1)—The most important result of the careful removal 
of the matrix from the skull is that the structure of the palate is completely revealed, 
the bones being perfect and very little displaced. The taxonomic importance of this 
