162 Annals of the South African Museum. 



on the left side. It is much smaller than the surangular, and is 

 almost entirely confined to the inner side of the jaw. The splenial 

 is very well developed and fairly well preserved. It forms the inner 

 side of the jaw in front of the coronoid and the angular. The 

 articular is not preserved. 



For this new type I have proposed the name Protewsuchus fcrgusi. 



Affinities of Protcrosuchus. 



Proterosuchus differs so very greatly from any form hitherto dis- 

 covered that it is a little difficult to decide as to its affinities, and the 

 difficulty is made the greater by the very imperfect condition of the 

 remains. There are four reptilian orders with which it shows more 

 or less affinity, viz., the Crocodiha, the Dinosauria, the Pterosauria, 

 and the Ehynchocephalia. It is highly probable that the Crocodiles, 

 the Dinosaurs, and the Pterodactyles are all descendants of Ehyn- 

 chocephalian ancestors, and the early forms of each order so much 

 resemble each other, and also the Rhynchocephalians, that it is often 

 a matter of great difficulty to say to which of the four orders an early 

 genercxlised type really belongs. Were only the exterior of the skull 

 of Proterosuchus known, one might readily agree to place it some- 

 where near Ornithosuchus in the Parasuchia or other division of the 

 early Crocodiles, but the structure of the palate and the lower jaw 

 shows that the affinities are more with the early Ehynchocephalians. 

 In all known Crocodilians, Dinosaurs, and Pterodactyles teeth, if 

 present, are confined to the margins of the jaws, and never appear on 

 the pre vomers or pterygoids. Among Ehynchocephalians, on the 

 other hand, teeth are usually present on the prevomers and pala- 

 tines, and often also on the pterygoids. In the most primitive 

 Ehynchocephalians — -Palaeohatteria and Proterosaurus — the palate 

 is very imperfectly known ; but in Procolophon, which is moderately 

 nearly allied to Palaeohatteria, the palate has a number of teeth on 

 each prevomer, and two rows of small teeth on each pterygoid. On 

 the palatines in Procolophon, on the other hand, there are no teeth. 

 Though Procolophon is not very nearly allied to Proterosuchus, it is 

 interesting to observe that in general type the palates are essentially 

 similar in the two. In Procolophon there are no teeth along the 

 external pterygoid process, but in Dimetrodon a row of teeth is seen 

 very much as in Proterosuchus ; and the Pareiasaurians, though 

 farther removed from the Ehynchocephalians, frequently retain this 

 row of teeth along the pterygoid process, e.g., Pareiasaurus and 

 Pariotichus. It would thus appear that the palate of Proterosuchus 



