48 Annals of the South African Museum. 



Length of nostril 27 mm. 



Internasal breadth 31 



Preorbital length 217 ,, 



Length of orbit 24-5 , , 



Interorbital width 90 ,, 



Length of frontal 160 ,, 



Length of nasal 149 ,, 



Length of parietal 114 ,, 



The premaxillae are divided from one another by a median suture, 

 and posteriorly they are separated for half their length by the nasals. 

 They form most of the snout, and the whole of the anterior borders 

 of the nostrils. Midway between the front of the nasals and the 

 snout the premaxillary suture is pierced by a small fenestra, which 

 apparently contains no bone corresponding to the internasal described 

 by Watson in Micropholis stowi. A fracture obliquely across the 

 nostrils shows the premaxilla lying outside the septomaxilla and 

 below and within the maxilla, articulating with the latter by a 

 complex suture. 



The maxilla extends for a length of 308 mm. from the premaxilla 

 back to the quadrato-jugal. It is a narrow bone, tapering out 

 posteriorly from a maximum height of 27 mm. just behind the 

 septomaxilla. 



The septomaxilla appears on the surface of the face for a distance 

 of 11 mm. behind the nostril, and forms almost the whole of the 

 posterior border of the nostril, the nasal just entering into the border 

 on the superior edge, The septomaxilla meets the maxilla and the 

 nasal, but not the lachrymal. Its cheek portion has a triangular 

 form. It forms the floor of the nostril, and extends downwards 

 inside the maxilla and premaxilla. 



The nasal is a large bone articulating with the premaxilla, septo- 

 maxilla, maxilla, lachrymal, prefrontal, frontal, and interfrontal. 

 Anteriorly and between the nostrils it is comparatively narrow ; 

 in the middle it widens out to form the whole of the upper surface, 

 while posteriorly it tapers, being separated from its neighbour by the 

 interfrontal and frontals. 



The interfrontal is a median rhombic bone, 50 mm. long and 

 9 mm. broad, articulating for half its length with the nasals and 

 for half with the frontals. Broom has recently described this bone 

 in Eryops, and it is known to occur in a number of small Stego- 

 cephalians. Unfortunately the type of Trematosaurus kannemeyeri 

 does not show this region. If an interfrontal did occur in that 



