South African Fossil Reptiles and Amphibia. 215 



The discovery of the close relationship between Diademodon 

 and Cynosuchus whaitsi from the Cistecephalus zone renders it 

 probable that the line of descent of the Cynognathidae, if it passed 

 through any of the Gorgonopsia at all, must have passed through 

 some early form ; the larger forms from the Cistecephalus and 

 Endothiodon zones cannot be as close to that line as has hitherto 

 been supposed. 



The position of the Therocephalia is uncertain. The brain- 

 case in the Bauridae and the Scaloposauridae is not known in 

 detail ; but it seems probable that some Therocephalian of the 

 lower zones gave rise to the Scaloposauridae of the Cistecephalus 

 zone and these in turn to the Bauridae of the Upper Beaufort 

 Beds. Further, the Therocephalia studied seem to approximate 

 to the Cynognathidae in the absence of the transverse wall behind 

 the pituitary fossa and in the presence of a plate-like epipterygoid. 



