32 UPPER CRETACEOUS TELEOSTS 
a deep depression above the hyomandibular facet; this depression is the dilatator 
fossa. 
The pterotic forms the postero-lateral border of the skull-roof, and bears a high 
crest which arises antero-medially and terminates at the posterior end of the lateral 
edge of the bone. This crest forms the boundary between the dilatator fossa laterally 
and the post-temporal fossa medially. The post-temporal fossa is unroofed. The 
otic branch of the infraorbital sensory canal passed within the pterotic crest. Above 
the hyomandibular facet, the postero-lateral part of the pterotic crest bears two 
large pores. The larger of the two is more ventrally placed and through it passed 
the preopercular sensory canal ; the upper, smaller pore received the lateral-line 
canal from the post-temporal bone. 
The epiotic forms the posterior edge of the lateral region of the skull roof medial to 
the post-temporal fossa. On the upper region of the epiotic there is a thickened 
region with which the dorsal limb of the post-temporal articulated. The parietal 
lies in front of the epiotic and contacts the frontal anteriorly. The post-temporal 
fossa is composed medially of epiotic, parietal and frontal, and laterally of pterotic. 
These bones meet in the mid-ventral line of the post-temporal fossa. 
The parasphenoid can be seen in the base of the orbit and is expanded laterally into 
flanges which associate with the endopterygoids. Due to the deepening of the neuro- 
cranium posteriorly, the parasphenoid ascends sharply beneath the orbits to pass 
between the lateral ethmoids. 
Jaws and suspensorium. The hyomandibular is long and narrow with a well 
marked head. Anteriorly the head is expanded and rounded to fit into the cup- 
shaped depression between the sphenotic and prootic. The posterior part of the hyo- 
mandibular head is elongated, narrow and fits into the groove on the pterotic. The 
axis of the hyomandibular is inclined slightly forwards ventrally, as is the quadrate, 
thus the mandibular articulation lies below the middle of the orbit. The lateral face 
of the hyomandibular bears a large crest in its upper region. This crest arises from 
the anterior region of the head and passes sharply back to the posterior edge of the 
bone which it follows ventrally. The upper edge of the preoperculum rests against 
the rear face of this crest. Ventrally the hyomandibular tapers to end some distance 
above the quadrate. The symplectic is a long ventrally tapering bone contacting 
the hyomandibular dorsally and the quadrate ventrally. 
The metapterygoid overlaps a large part of the lateral face of the hyomandibular, 
and meets the dorsal edge of the quadrate ventrally. The metapterygoid bears an 
oblique crest near its anterior border. 
The quadrate is irregularly triangular with its posterior edge practically horizontal. 
The condyle is small and transversely orientated. The posterior edge of the quad- 
rate rests upon the anterior projection of the preoperculum. Both the metaptery- 
goid and the quadrate meet the ectopterygoid anteriorly. 
The ectopterygoid runs upwards from the quadrate at an acute angle to contact the 
palatine below the lateral ethmoids and to support the endopterygoid medially. 
The palatine is enormously elongated, extending the whole length of the snout 
region. It is relatively deep posteriorly but shallow anteriorly. The palatine is 
