20 UPPER CRETACEOUS TELEOSTS 
from the centre of ossification. Postero-laterally the frontal meets the sphenotic 
above the hind end of the orbit and posterior to this is overlapped by the medial 
extension of the anterior region of the pterotic. The extreme anterior extent of the 
pterotic roofs the anterior end of the post-temporal fossa, while the frontal also 
contributes to the antero-medial walls and roof of the fossa. The ventral surface of 
the frontals bears a broad median channel which is bridged posteriorly by the orbito- 
sphenoid and the pleurosphenoids. 
The parietals are partially separated in the mid-line by the expansion of the supra- 
occipital, but meet anterior to the supraoccipital in a short suture. Each parietal 
bears a shallow, transverse crest which contacts its fellow in the mid-line. The 
lateral extremities of these crests join with the ridges passing back on to the parietals 
from the frontals. The combined crests so produced pass postero-laterally from the 
parietals on to the epiotics, terminating on the rear edges of the neurocranium above 
the post-temporal fossae. Laterally the parietal is overlapped by the medial ex- 
tension of the pterotic in the roof of the fossa. 
The supraoccipital is large and appears on both the posterior and dorsal faces of the 
skull. Laterally the supraoccipital meets the epiotics on both the dorsal and post- 
erior surfaces of the neurocranium. Ventrally on the posterior face of the skull the 
supraoccipital contacts the exoccipitals. From the rear face of the supraoccipital 
a moderately large crest projects posteriorly but does not rise above the plane of the 
skull-roof. 
The epiotics form part of the occipital border, contacting the parietals anteriorly 
and being overlapped by the medial extension of the pterotic. On the posterior face 
of the neurocranium the epiotics contact the exoccipitals ventrally. The lateral sur- 
face of the epiotic forms the posterior part of the medial wall, roof and floor of the 
post-temporal fossa. The fossa is complete and opens by a discrete fenestra on the 
posterior face of the neurocranium. Its roof and medial wall are composed of frontal, 
parietal and epiotic while the lateral part of the fossa seems to be composed solely of 
pterotic, but there may possibly be inclusions from the sphenotic and the prootic in 
the anterior region of the fossa. On the dorsal surface of the epiotic just medial to 
the post-temporal fossa, the epiotic is thickened into a slight knob which provides the 
articulatory facet for the dorsal limb of the post-temporal. 
The sphenotic contacts the frontal laterally and forms the upper posterior border 
to the orbit. The dorsal surface of the sphenotic is excavated and smooth and forms 
the anterior part of the ill-defined dilatator fossa. Near to the lateral edge of the 
sphenotic a small foramen may have transmitted a branch of the otic nerve. 
The pterotic joins the sphenotic anteriorly in the dilatator fossa and extends 
medially above the post-temporal fossa. The pterotic inclines ventro-laterally, and 
has a shallow postero-laterally directed crest along its entire length. 
The supraorbital sensory canal ran within the frontals anteriorly above the orbit 
and posteriorly back towards the parietal. Several subsidiary branches of the main 
canal passed on to the smooth medial region of the frontal and there might have 
been a complete frontal commissure, as in Aulopus (p. 204), and many other mycto- 
phiforms (Gosline, Marshall and Mead, 1966: 7). The lateral line canal entered 
