South African Fossil Reptiles and Amphibia. 



209 



is a small foramen leading into a canal which passes up through 

 the body of the bone into the hypophysial fossa. This is possibly 

 a carotid foramen. 



The pro-otic forms the posterior and part of the ventral borders 

 of the pituitary fossa. Superiorly it is pierced by the incisura 

 pro-oticum and posteriorly it forms with the inner end of the 

 opisthotic the border of the. oval foramen lying between the post- 

 temporal fossa and the incisura pro-oticam. 



The epipterygoid is preserved on the left side of the specimen. 

 Its ventral end is a broad thin plate and is supported by the posterior 

 horizontal ramus of the pterygoid, from which it seems to be dis- 

 tinctly separated. Superiorly the bone soon becomes a small rod, 

 oval in cross-section, and covering the incisura pro-oticum. 



ft Or 



GORGONOGNATHUS LONGIFRONS Htn. 



FIG. 56. Back half of type skull sectioned vertically, seen from 

 right and showing some of the foramina, x ^ nearly. 



FIG. 57. Back half of type skull sectioned vertically near median 

 line, seen from left, x ^ nearly. 



Gorgonognathus longifrons. The type-skull of this species shows 

 one or two further details. The back half of the skull has been 

 split by a slightly oblique longitudinal vertical section through 

 the middle of the occipital condyle, but it has been impossible 

 owing to the extreme hardness of the matrix to clear the 

 cavities. 



The posterior part of the brain-case is of the same type as in the 

 previous skull, but the process of the pro-otic forming its anterior 

 boundary is rather more vertical and somewhat longer. Posterior 

 to its upper end on the side-wall is seen the incisura pro-oticum 

 and, separated from that by a thin splint of bone, is the large 

 irregular foramen which has been considered venous. Superiorly 

 the prootic meets the descending plate of the parietal ; but just 



