182 UPPER CRETACEOUS TELEOSTS 
rounded, posteriorly directed flange. The dorsal surface of this flange provides the 
region of articulation for the dorsal limb of the post-temporal. 
The mesethmoid is peculiarly shaped, appearing as two distinct portions, an 
anterior short, straight rod-like piece forming the extreme anterior termination of 
the snout ; and a much expanded posterior region. This posterior region is in the 
form of two narrow, flattened wing-like expansions which are directed postero- 
laterally and inclined ventro-laterally. The lateral edge of each mesethmoid wing 
is attached to the dorso-medial region of each palatine. 
The vomer closely parallels these lateral extensions of the mesethmoid and is 
attached to its ventral surface. The vomer is more extensive than the mesethmoid 
and gradually narrows posteriorly to contact the parasphenoid in the region of the 
lateral ethmoid. The palatine appears to be associated with the edge of the vomer 
which supports numerous teeth. 
The parasphenoid is visible within the orbit where it is slightly expanded into 
lateral flanges which overlap the medial edges of the endopterygoids. Anteriorly the 
parasphenoid passes between the lateral ethmoids and attaches to the posterior end 
ofthe vomer. The lateral ethmoids meet the ventral region of the frontals delimiting 
the orbit anteriorly. They expand ventrally and are attached to the upper posterior 
end of the palatine. 
Hyopalatine bones. The hyomandibular is large with an elongated head. The 
anterior part of this head is thickened and so shaped as to fit into the anterior cup- 
shaped part of the hyomandibular facet. The remainder of the head is much thinner 
and almost straight. The posterior edge of the hyomandibular is backwardly 
curved, but the posterior edge of the quadrate curves forwards so that the condyle 
occurs immediately below the occiput. The outer face of the hyomandibular bears 
one relatively prominent crest arising from the anterior region of the head and 
passing postero-ventrally to the hind edge of the bone. 
Fic. 84. Pyrionolepis cataphractus (Pictet & Humbert). Restoration of the skull in 
lateral view. 
