South African Fossil Reptiles and Amphibia. 51 



lates with the premaxilla in front, and with the palatine and para- 

 sphenoid behind. Arising from a depression in front of the posterior 

 nares is a large tusk, with a basal diameter of 20 mm. and a height 

 of about 33 mm. the largest tooth in the skull. Lying along the 

 wall of the posterior opening is a series of 8 smaller teeth, elliptical 

 in section, with the long axis of the ellipse lying at right angles to 

 the mid-plane of the palate. These teeth are separated from each 

 other by elliptical pits, now filled with calcite crystals. There is no 

 evidence of minute prevomerine teeth. 



The palatine forms the hinder border of the posterior nares, and 

 articulates with the prevomer, the maxilla, and the transpalatine. It 

 carries three large tusks in an antero-posterior line, of which the 

 first is the largest. 



The transpalatine lies along the inside of the maxilla, articulating 

 with the pterygoid behind and the palatine in front. It carries a 

 row of teeth of varying size. 



The pterygoid is a large bone, diverging in three directions from 

 a central plate at the back. Interiorly it is loosely articulated with 

 the flat portion of the median bone which is presumably the para- 

 sphenoid ; posteriorly it passes upwards and backwards partially 

 to wrap round the quadrate, and meets the squamosal ; anteriorly 

 and externally it meets the transpalatine in a long articulation. 

 Behind this last articulation it is covered with a number of minute 

 pointed teeth almost to the plane of the back of the large vacuity. 

 It also has a short articulation externally with the maxilla. 



The parasphenoid has the form of a large median thin plate at the 

 back of the palate, which passes forward to the prevomers. These 

 pass backwards on both sides of the lower part of the bone for some 

 distance as thin bones with long articulating inner surfaces. A 

 section across the skull between the orbits and the nostrils shows 

 the parasphenoid lying above the prevomers and sending down a 

 small process between them. A section across the parasphenoid at 

 the front of the parietals shows a vertically elongated oval with two 

 wing-like projections superiorly not passing to the bones of the 

 cranium. Between these projections and the mass of the bone I 

 can detect no sutures. Posteriorly the parasphenoid plate sends up 

 a short process to meet the downward projection of the exoccipital. 



The occiput is broken away in part, and neither the basisphenoid 

 nor basioccipital can be detected. The exoccipital seems to have 

 played the most prominent part in the formation of the occipital 

 condyle. 



