: 
ESPECIALLY MYCTOPHOIDS 79 
anterior opening of the canal is practically within the hind limit of the orbit. The 
remainder of the branches of the trigeminal and facial nerves did not enter the 
pars jugularis, but all passed through a single foramen in the hind wall of the orbit 
dorso-medial to the anterior opening of the pars jugularis. A notch occurs on the 
medial edge of the bone above the prootic bridge, this might indicate the course of 
the oculomotor nerve. 
The pleurosphenoids, in the postero-dorsal region of the orbit, are separated in the 
mid-line by the large optic fenestra. Each bone meets the frontal dorsally and the 
prootic and sphenotic posteriorly. Beneath the frontals the bone is splayed apart 
and the superficial sheets of bone produced fail to contact the frontals medially. 
This area was in life presumably filled by cartilage. 
The occipital condyle is circular and deeply concave. Ventrally it is formed of 
basioccipital. This single median bone passes forwards above the parasphenoid to 
meet the prootic anteriorly and the exoccipitals dorsally. In the angle between the 
condyle and the lateral region of the basioccipital there is a small group of pits and 
ridges. Internally the basioccipital forms the myodome roof and the floor to the 
otolith chamber. The basioccipital passes antero-dorsally to meet the prootics, 
separating the otolith chambers from the myodome. Dorsally the basioccipital 
bears a slight median crest which serves partially to separate the otolith chambers. 
The otolith chambers themselves extend anteriorly and end in a recess just posterior 
and ventral to the internal opening of the facial foramen. 
pef 
Fic. 35. Enchodus lewesiensis (Mantell). Neurocranium in posterior view. 
