50 



Annals of the South African Museum. 



central half of the upper part of the occipital plate. Its lower 

 occipital border articulates apparently wholly with the exoccipital. 



The tabulare forms the outer upper angle of the occiput. It 

 appears on the upper cranial surface, articulating with the squamosal, 

 suprasquamosal, and postparietal. It forms most of the upper 

 border of the lateral occipital foramen, and part of the outer and 

 lower border ; but owing to fracturing and splintering of the bones 

 its articulation with the paroccipital is difficult to ascertain exactly. 



The squamosal is larger than the suprasquamosal. Above it articu- 

 lates with the postorbital, suprasquamosal, and tabulare, and below 

 with the jugal and quadrato-jugal. 



The quadrato-jugal is a large bone forming the posterior angle of 

 the skull. Anteriorly it passes forward to the maxilla, articulating 

 with the jugal and squamosal. It is bent to form part of the back 



FIG. 6. Trematosaurus sobeyi, Haughton. Diagram of section of skull just 

 anterior to the orbits, x . 



surface of the angle, and overlaps the quadrate, which is also over- 

 lapped on its inner border by the squamosal and pterygoid. 



Both the premaxilla and maxilla bear teeth of more or less uniform 

 size. Near the front of the snout the premaxilla carries two slightly 

 larger teeth, of which the first is 15 mm. long and recurved. There 

 are 10 other smaller teeth on the premaxilla. The maxillary teeth 

 are about 50 in number, borne in a row along the whole length of 

 the bone, the final teeth being slightly the smallest. The average 

 length of the larger teeth is about 10 mm., and they are arranged 

 fairly evenly along the bone, 10 teeth below the orbit occupying 

 .a space of 26 rnm. 



The palatal view of the skull shows some interesting features. 

 The premaxilla extends back for a distance of about 50 mm. from 

 the front of the palate, and articulates behind with the prevomer. 



The prevomer is a large bone, forming the inner and anterior walls 

 of the posterior nares, and most of the front of the palate. It articu- 



