206 



Annah of the South African Museum. 



that the whole cavity for the cerebellum is much smaller, and 

 that its base rises very rapidly in front, very much as it does in 

 Dimetrodon. The pro-otic, although it extends further forward 

 than in Anomodonts and Dimetrodon, has more of the greater 

 anterior projection which, occurring in Diademodon and also in 

 OrnithorhyncJtus, has a long suture with the parietal." 



SCYMNOGNATHUS TIGRICEPS ? 



FIG. 55a. Diagrammatised sagittal section through back part of 

 skull No. 4334. 



FIG. 55b. Section across vestibule of same. Both figures x ^. 



In the skull of Scymnognathus mentioned above (S.A. Mus. Cat. 

 No. 4334) the occipital condyle is crushed, so that seen from 

 behind it forms but a half-ring below the small foramen magnum. 

 It is actually a large condyle with a central notochordal pit. The 

 basioccipital is fairly thin. It seems to play little or no part in 

 the border of the foramen magnum. 



The paroccipital process has a concave lower border. It is 

 higher in front than behind. Its upper surface forms the lower 

 border of the small post-temporal fossa which lies on the level 

 of the middle of the foramen magnum. The foramen jugulare 

 is bounded above by the paroccipital and below by the exoccipital 

 and looks almost entirely downwards. The front face of the par- 

 occipital process is fairly flat and forms the posterior border of 

 the fenestra ovalis, which lies at about the level of the notochordal 



