44 UPPER CRETACEOUS TELEOSTS 
opening. The otic nerve passed dorso-laterally on to the undersurface of the sphen- 
otic to enter the bone through a small foramen. The superficial ophthalmic nerves 
passed antero-dorsally within a groove continuous across the face of the pleuro- 
sphenoid to the ventral surface of the frontal. The profundus nerve does not appear 
to have entered the pars jugularis, there being a small foramen in the hind wall of the 
orbit medial to the anterior opening of the pars jugularis which may have transmitted 
it. The oculomotor nerve passed out of the cranial cavity through the optic fenestra 
and its passage is marked by a deep notch on the medial edge of the prootic just above 
the prootic bridge. The palatine nerve, which entered the pars jugularis through the 
facial foramen, passed out through a canal in the floor of the pars jugularis. This 
palatine canal is confluent with the canal transmitting the orbital artery up into the 
pars jugularis. Within the myodome, part of the internal wall of the canal is absent 
so that the confluence of the two canals is clearly shown with that of the palatine 
nerve entering the myodome and that of the orbital artery entering from the lateral 
face of the prootic. Two further very small foramina are found in the lateral wall of 
the prootic dorsal to the foramen of the orbital artery. One of these opens into the 
same canal which housed the orbital artery and palatine nerve, and could possibly 
have transmitted a subsidiary branch of the palatine nerve. More likely, however, 
the two foramina transmitted a small artery and vein supplying the muscle masses in 
the area above the prootic. The foramen for the abducens nerve is postero-medial to 
the facial foramen, and the nerve passed ventrally into the myodome. 
The exoccipitals meet in the mid-line of the posterior face of the neurocranium both 
above and below the wide, shallow foramen magnum, completely enclosing it. It has 
already been noted that the exoccipitals do not enter into the composition of the 
occipital condyle but each exoccipital is considerably thickened at the lower corners 
of the foramen magnum. Several small foramina are found in the exoccipital on 
either side of the foramen magnum and these probably transmitted occipital nerves to 
Fic. 19. Cimolichthys levesiensis Leidy. Neurocranium in posterior view. 
From B.M.N.H. number P.181r. 
