186 Annals of the South African Mn^tuin. 



The parietal forms the main portion of the parietal crest and 

 is almost entirely a vertical bone. Lying behind it on the occipital 

 plate is a large interparietal which articulates below with the 

 supra-occipital and laterally with the tabulare. 



The jugal forms the lower border of the orbit and extends back 

 to meet the squamosal. 



The occipital condyle is large and moderately thick and does 

 not extend very far up the sides of the foramen magnum. It 

 is shallower than that of Arctops and thicker than that of Scym- 

 noc/xatkus figured by Watson. It is not certain to what extent 

 the exoccipitals participate in the formation of the condyle, but 

 certainly it is for the most part formed of the basioccipital. 



The exoccipital differs from that of Arctops it is a small tri- 

 angular bone forming the upper border of the foramen jugulare 

 and lying behind the paroccipital process. It plays no part in 

 the boundary of the post-temporal fossa, and is well marked off 

 from the paroccipital process. 



The suture between the basioccipital and basisphenoid can be 

 seen a limit 31 mm. in advance of the back of the condyle. The 

 mass of the basisphenoidal tubera, which are not extremely large 

 although quite prominent, is formed bv the basioccipital. the 

 basisphenoid lying below as in the Dicynodonts. Jjetween the 

 tubera the basioccipital is flat. Laterally the bone presumably 

 articulates with the opisthotic, but the suture is not visible. 



The foramen jugulare lies at a level just above the bottom of 

 the condyle and faces entirely backwards. Its upper border is 

 formed by the exoccipital, but in the main it lies in the paroccipital. 

 whose posterior face is hollowed out horizontally on the outer 

 side of the foramen. 



The post-temporal fossa lies at the level of the middle of the 

 foramen magnum ; consequently the paroccipital, which is long, 

 is more massive than in Scymnognathus tchaitsi and less so than 

 in Arctops. 



The fenestra ovalis is an irregular-shaped opening, unbounded 

 by bone on the outer side and lying some distance out from the 

 basisphenoidal tubera, below the level of the occipital condyle. 



Just in front of its suture with the basioccipital the basisphenoid 

 forms a strong median keel which is continued forwards between 

 the pterygoid vacuities by the pterygoids. The exact junction 

 between the basisphenoid and the* pterygoids is difficult of de- 

 termination on account of fracturing in this region ; but the 



