40 UPPER CRETACEOUS TELEOSTS 
The parietals are narrow, transversely orientated strips of bone, which laterally 
form part of the medial wall of the post-temporal fossa, meeting the pterotic anteri- 
orly and the epiotic posteriorly. The post-temporal fossa itself is small and appears 
to be only partially roofed. Posteriorly where the fossa is unroofed it is bounded 
medially by the epiotic and the parietal, and laterally by the pterotic. 
The epiotics form part of the occipital border of the skull-roof, bounding the pari- 
etals posteriorly. On the posterior face of the neurocranium they are separated 
medially by the supraoccipital, and ventrally contact the exoccipital. Within the 
posterior region of the post-temporal fossa, the epiotic meets the pterotic in the mid- 
line of the floor of the fossa. The whole occipital border of the roof is angled sharply 
backwards from the midpoint on the supraoccipital, the epiotic forming the termina- 
tion of this backward extent. 
The sphenotic extends laterally from beneath the frontal in the posterior orbital 
region and is smooth and unornamented. A slight crest originates on the sphenotic 
and extends posteriorly to be continued on the pterotic, the whole extent of this crest 
forming the postero-lateral border of the skull-roof. 
The pterotic forms the postero-lateral part of the roof of the skull and bears two 
dorsal crests. The lateral crest is the continuation of the crest on the dorsal surface 
of the sphenotic, whilst the more medial crest originates beneath the lateral edge of 
the frontal and extends postero-laterally to connect with the lateral crest about mid- 
way along the length of the pterotic. This medial crest forms the posterior edge of 
the incomplete roof to the post-temporal fossa, and the combined crests posteriorly 
form the lateral boundary of the unroofed portion of the post-temporal fossa. 
The supraorbital canal passed forwards within the frontal giving rise to several 
subsidiary branches which passed on to the surface of the frontal. Two branches 
passed postero-medially from the region of the centre of ossification, a further branch 
passed antero-medially and opened on to the interorbital area through a slit-like 
opening. The main supraorbital canal continued anteriorly within the frontal. 
The infraorbital sensory canal appears to have passed through part of the dorsal sur- 
face of the sphenotic and opened on to the surface medial to the sphenotic crest. The 
otic branch of the infraorbital sensory canal entered the pterotic crest postero-lateral 
to the rear end of the post-temporal fossa and passed forwards within the crest. The 
tube which contained the sensory canal opens anteriorly on the surface of the pterotic 
in the angle between the two pterotic crests. The contained sensory canal passed 
forwards on the surface of the pterotic and the sphenotic to connect with the main 
infraorbital canal on the dorsal surface of the latter bone. A supratemporal com- 
missure does not appear to have been present. 
On the edge of the frontal, in the anterior orbital region, a small supraorbital bone 
is present. The supraorbital bears an external ornamentation of raised ridges of 
bone radiating ventrally from a point near to the mid-dorsal border. 
The mesethmoid is prominent but not heavily ossified. It extends from the an- 
terior end of the frontals and ends in an acute point. Its basic form is that of two 
laminae of bone fused irregularly in the anterior region and diverging posteriorly to 
lie alongside the antero-lateral edges of the frontals. The two backwardly divergent 
