South African Fossil Reptiles and Amphibia. 203 



The most striking feature is the smallness of the brain-cavity 

 compared with the immense thickness of the roofing-bones'of the 

 skull and of those of the occipital plate. The foramen magnum 

 is small, oval in shape, higher than wide. In front of it the brain- 

 cavity is not much enlarged, sloping gently upwards as an almost 



VT. 



fir Poss 



FIG. 54. Median section through the back part of skull of a large 

 Tapinocephaloid. (S. A. M. Cat. No. 750.) x 1 nearly. 



uniform tunnel to the exit for the Vth nerve. This cavity is 

 throughout higher than wide. The posterior portion of the con- 

 dyle is weathered away ; but just anterior to the posterior face as 

 preserved there is a small foramen in the side wall of the brain. 

 This probably transmitted a vein. Anterior to it the floor of the 

 brain-case is excavated on each side. The hollow thus formed is 

 divided into two parts by a bony plate protruding from the lateral 



