PR0C0L0PH0N FROM THE CAPE COLONY. 807 



the same general form, and the median roof-bones double, with 

 orbits, nares, and foramen parietale similarly placed. The chief differ- 

 ences are that (1) in the fossil the region of the temporal fossa is 

 covered by expansions of the frontal, parietal, and postfrontal bones ; 

 but since in Podocnemys this is only a generic variation from the 

 Emydian type, there is no reason for attributing more than generic 

 importance to it in the fossil ; (2) the malar bone in the fossil is 

 expanded so as to cover most of the vacuity which exists in the 

 living type between that bone and the squamosal ; (3) in the fossil 

 the posterior outline of the skull is straight. There are many im- 

 portant points upon which further information must be obtained 

 before the position in the series of Procolophon can be finally 

 settled ; but, in the present state of knowledge, I see no reason to 

 hesitate, on the evidence detailed, in regarding it as a fossil Ehyn- 

 chocephalian. As such, it adds another link to the evidence that 

 the Ehynchocephala constituted one of the most widely diffused 

 types of terrestrial life in the Triassic period. 



EXPLANATION OF PLATE XXXIL 



Procolophon Griersoni. 



Ftg. 1. Skull, seen from above. 



Fig. 2. Lateral view of same skull with lower jaw. 



Fig. 3. Anterior view of skull, showing divided nares. 



Procolophon laticeps. 



Fig. 4. Anterior part of skull, seen from above. 

 Fig. 5. Lateral view of same skull. 



Fig. 6. Vertical section of same skull through quadrate bone, lower jaw, brain- 

 cavity, basisphenoid and pterygoid bones. 



Frocolophon cuneiceps. 



Fig. 7. Skull, seen from above. 

 Fig. 8. Lateral view of same skull. 



(a, parietal foramen ; b, orbit ; c, nostril ; d, lower jaw ; e, quadrate bone ; 

 /, basisphenoid ; g, pterygoid bone.) 



Discussion. 



Mr. Hulke accepted Prof. Seeley's views on the structure of the 

 skull of Procolophon, and agreed with him as to the difficulty of 

 regarding the Theriodontia as forming a distinct Order of the 

 Beptilia. 



