MAMMAL-LIKE REPTILES. 753 
occipital forms a vertical area, which may be very high and wide 
(text-fig. 7) (R. 3596) or comparatively small. The sides of this 
area must be formed by the paroccipitals for some distance, as 
the fenestre ovales lie at the sides well below the condyle. The 
corresponding flat area in front is formed by the basisphenoid. 
There are no distinct tubera basisphenoidalia, or basipterygoid 
processes, but the posterior ends of the pterygoids articulate and 
indeed fuse with the lower margin of the vertical area. From 
Text-figure 3. 
} 
(Ce fi i ’ ip Wr SQ. 
VS Borin Dy * Se 
Mormosaurus seeleyi. Posterior view of the type-skull, x 4. 
Reference-letters as before, with :—B.Oc., Basioccipital; Par.Oc., Paroccipital ; 
P.T.F., Post-temporal fossa; Sr., Stapes. 
between them the narrow parasphenoid rises as a vertical plate, 
separated from much of the front of the basisphenoid by the deep, 
short notch which is the pituitary fossa. This fossa is bounded 
laterally by very low ridges which run upwards on the vertical 
anterior face of the basisphenoid until they terminate in low pro- 
cesses which are the processi anteriores prootici. The prootic of 
course contributes to the fenestra ovalis, above which it is 
perforated by the aqueeductus fallopii for the VIIth nerve. 
The otic and supraoccipital regions of the skull are in contact 
with the following bones :— 
The upper outer corner of the posterior face of the large 
paroccipital process with the tabulare. 
The outer end and front face of the paroccipital process with the 
squamosal. 
The lower part of the front face of the paroccipital process with 
the quadrate. 
The posterior surface of the supraoccipital region is covered by . 
the interparietal and tabulares. Its upper margin (and part of 
the front face?) by the parietal (and postorbital 2). 
