88 UPPER CRETACEOUS TELEOSTS 
postero-dorsally of the remains of a subocular shelf. The infraorbital bones decrease 
in length posteriorly, but not in width, none of the bones bearing any posterior 
expansion. The whole circumorbital series is ornamented with scattered tubercles 
which are most prominent above the course of the infraorbital sensory canal. 
Hyopalatine bones. The general configuration of the hyopalatine bones is visible 
but the more detailed composition is masked by the covering of the dermal elements 
of the jaws, and by the rather poor state of preservation of the hyomandibular. 
The hyomandibular is large and deep with an antero-posteriorly elongated head. 
The posterior edge of the hyomandibular bears the condyle for the articulation of the 
operculum in its upper third. The lowermost two-thirds of the hyomandibular 
support the leading edge of the preoperculum. The lateral face of the hyomandi- 
bular is crossed by a crest which arises at the anterior region of the head and passes 
postero-ventrally in a curve to meet the rear margin about midway down. 
The quadrate condyle is prominent and transversely orientated. Postero- 
dorsally the quadrate is indented, the posterior border of the excavation being lower 
than the remainder of the upper margin. This indentation marks the uppermost 
region of the recess on the medial face of the quadrate which housed the symplectic. 
The symplectic is present as a narrow rod of bone in B.M.N.H. number P.4748. 
The pterygoid bones are indistinct. The ectopterygoid is a straight, laminate 
bone meeting the quadrate posteriorly and articulating with the palatine anteriorly. 
A single row of prominent teeth is present on the ectopterygoid. The endopterygoid 
can be seen within the orbit close to the parasphenoid where it forms part of the 
roof of the mouth. The metapterygoid is large, overlying the margin of the hyo- 
mandibular, but attaching ventrally to the dorsal edge of the quadrate. 
The palatine is the characteristic tumid bone with an enlarged terminal fang at go° 
to the axis of the bone. Posteriorly the palatine extends dorsally where it articu- 
lates with the lateral ethmoid internal to the lachrymal. Anteriorly the palatine is 
closely associated medially with the mesethmoid and vomerine regions. The head 
of the maxilla is just visible above the premaxilla, anterior to the lachrymal, lying in 
an oblique groove on the lateral face of the palatine. The terminal tooth is laterally 
compressed and bears fine longitudinal striations. 
Dermal upper jaw. The dermal upper jaw is shown in lateral view in Text-figure 
39. It is composed of two bones, the premaxilla and the maxilla. The premaxilla 
is large and has two regions fused at 90° to each other. Anteriorly, lying in the same 
plane as the skull-roof, there are the premaxillary pedicels which meet each other in 
the mid-line and rest upon the anterior edge of the mesethmoid. Each pedicel 
contains an elongated oval fenestra within it. The remainder of the premaxilla is 
positioned laterally and is triangular in form, being drawn out antero-posteriorly. 
On the anterior region of the lateral face near to the pedicel there is a groove running 
parallel with the plane of the pedicel. This groove is in line with the anterior opening 
of the supraorbital sensory canal on the frontal. The premaxilla is overlapped 
dorsally by the ventral expansion of the lachrymal bone. Ornamentation in the 
form of scattered tubercles is present on the outer face of the premaxilla, the pedicel 
being more strongly ornamented than the rest of the bone. The premaxilla tapers 
