South African Fossil Reptiles and Amphibia. 201 



may lead into foramina. Anteriorly the basisphenoicl narrows 

 and sends a short process forward between the pterygoids. On 

 each side is a short basi-pterygoid process which does not seem 

 to have the long slender splint lying on the inner side of the posterior 

 ramus of the pterygoid described by Watson in Diademodon. 

 The upper surface of the basisphenoid has a median groove. 



The side-wall of the brain-case does not differ in structure from 

 that of Diademodon. The suture between the prootic and the 

 epipterygoid (alisphenoid of Broom in Cynognathus) runs upwards 

 from the middle of the foramen which gives exit to the 2nd and 

 3rd branches of the Vth nerve to the sinus canal. The anterior 

 edge of the epipterygoid the suture between it and the pterygoid 

 is not easily seen is notched deeply by the opening transmitting 

 the II, III, IV, V and VI nerves. Superiorly it articulates with 

 the parietal. 



Fractures show cross-sections of the skull above the incisura 

 prooticum and just behind the orbit. In the former section are 

 seen two shallow plates of bone lying vertically between the 

 parietals and close together. In the second these two plates have 

 become much deeper, thinner, and somewhat further separated. 

 These are presumably crushed sphenoids or orbito-sphenoids. 



The front part of the palate has not been wholly cleaned ; but 

 there was certainly a nearly complete secondary palate, even if 

 the maxilla did not wholly meet its neighbour in the middle Hue. 

 The palatine is mainly a vertical bone. The ventral edge of the 

 bone medial to its suture with the maxilla is rugose. The presence 

 of a median vomer on the palate is not certain. The pterygoid 

 flange is large and descends considerably below the level of the 

 upper jaw. 



As far as can be seen this form is extremely closely allied to 

 Diademodon. The structure of the brain-case, the foramina for 

 the exit of the nerves, the double condyle, and the general " look '' 

 of Gynosuchus all bring it close to Diademodon, from which it is 

 separated stratigraphically by the whole thickness of the Middle 

 Beaufort Beds. The most important differences are that in 

 Cynosuchits 



1. the foramen jugulare is more widely separated from the 



fenestra ovalis ; 



2. the basipterygoid process of the basisphenoid does not 



send out a long splint to lie along the inner side of the 

 posterior ramus of the pterygoid ; 



