132 UPPER CRETACEOUS TELEOSTS 
soc 
pa 
_Somm_sy, 
bo 
Fic. 59. Halec eupterygius (Dixon). Neurocranium in posterior view. 
posterior angle of the lateral face of the neurocranium, and is thus visible both in 
posterior and lateral views. Postero-dorsally the intercalar has a facet for the 
ventral strut of the post-temporal. 
The sphenotic is large and well ossified and forms the postero-dorsal corner of the 
orbit. The sphenotic projects ventro-laterally from beneath the frontal contacting 
the pterotic posteriorly and the prootic ventrally. The epiotics appear on both 
dorsal and posterior surfaces of the neurocranium and are separated medially by the 
supraoccipital. The epiotic enters into the composition of the post-temporal fossa 
forming part of the medial wall and floor. The upper limb of the post-temporal 
articulates with the dorsal surface of the epiotic, medial to the posterior end of 
the post-temporal fossa. 
Hyopalatine bones. The hyopalatine bones are shown in medial view in Text- 
figure 60. The hyomandibular is large with a double head. The opercular process 
is ill-defined and approximately midway down the rear edge of the bone. The 
lateral face of the hyomandibular has a prominent lateral crest arising from the 
anterior head region and passing postero-ventrally to the rear edge of the bone. 
The preoperculum rests against the posterior face of this crest. The crest gradually 
shallows and disappears near to the ventral extremity of the bone. The anterior 
extent of the hyomandibular is thin and membranous and covered laterally by the 
metapterygoid. The hyomandibular tapers ventrally where it is circular in cross- 
section. The hyomandibular branch of the facial nerve entered the bone through 
an antero-dorsally directed foramen just below the head. Within the bone the 
nerve divided ; the opercular nerve came out near to the opercular process on the 
rear edge of the bone ; the hyoidean and mandibular nerves passed through foramina 
below the opercular process and continued ventrally on the posterior edge of the 
hyomandibular. 
