South African Fossil Reptiles and Amphibia. 199 



continue to the point of the crown. Behind the 4th incisor is a 

 diastema of 5 mm. which is followed by the large canine tooth. 

 This has a compressed oval cross-section with a longer antero- 

 posterior diameter of 8.5 mm. It, too, is unserrated. Closely 

 f olio wing the canine are the 8 molars (only 6 are preserved on 

 the left side). These occcupy a space of 25 ram. Speaking 

 generally, they decrease in size backwards ; but they are not of 

 equal age, the 2nd and 4th on the right side being probably im- 

 mature, as they are smaller than their neighbours on either side. 

 The 1st molar is to all intents and purposes a simple pointed tooth 

 with a convex anterior edge and a concave posterior one. On 

 the posterior edge there is a slight " step "' but no true cusp. 

 The 2nd has a slight protuberance on the posterior edge at about 

 midway down, so that the crown might be said to be formed of a 

 long pointed anterior cusp and a short blunt posterior cusp. On 

 the - r )th tooth the posterior cusp is much more pronounced, while 

 the 6th and 7th seem to possess two posterior cusps. The last 

 molar is a short simple tooth. A figure showing the details of the 

 molar dentition is given. 



The nostrils are somewhat higher than wide and are separated 

 l)\ a thin internasal septum formed by the premaxillae and the 

 nasals. The floor of the nostril is formed by a small septomaxilla 

 which appears only to a slight extent on the face. Between the 

 septomaxilla and the maxilla is an external foramen, seen in many 

 of the carnivorous Therapsida. 



The top of the skull is very similar to that of Diademodon. The 

 nasals are narrow anteriorly but broaden at their junction with 

 the lachrymals, and narrow again slightly between the prefrontals. 

 The prefrontal forms the anterior half of the supraorbital margin. 

 Posteriorly it unites with the postorbital to shut out the frontal 

 completely from the orbit. The frontal is a narrow bone broadest 

 anteriorly, and sending forward a narrow anterior lateral process 

 which separates for some distance the nasal from the prefrontal. 



The maxilla occupies most of the cheek andis pierced by a number 

 of small foramina. It passes back below the jugal to below the 

 middle of the orbit. ^ 



The lachrymal forms most of the anterior border of the orbit. 

 It is pierced just behind its suture with the maxilla by the lachrymal 

 foramen which communicates by a short canal through the bone 

 with a foramen within the orbit. Within the orbit there is also 

 another smaller foramen above the one referred to. 



