A Revision of the Reptiles of the Karroo. 365 



In the above classification it must not be considered that finality 

 has been reached. In dealing with extinct forms which are often very 

 imperfectly known it is impossible to do more than place many of 

 them in the system provisionally. Attention may be called to the 

 following points : 



Gorgonops, Titanosuckus, and the allied forms are provisionally 

 placed in the Therocephalia, of which they form a distinct family. 



The genera Oudenodon and Opisthoctenodon have been abandoned 

 as these supposed genera are now pretty certainly known to be the 

 females of Dicynodon and Pristerodon respectively, the presence or 

 absence of a tusk being evidently only a sexual character in these 

 types. 



Karoomys, which I have hitherto regarded as probably a mammal, 

 is perhaps rather more likely to be a Cynodont. 



Under Owen's order Thecodontia are grouped a series of primitive 

 reptiles which seem to be connected with the ancestral crocodiles. 

 The forms known probably belong to at least four sub-orders, but it 

 seems unwise to attempt any further classification at present. Heleo- 

 suchus griesbachi is Owen's Saurosternon griesbachi which is, in my 

 opinion, not at all allied to Saurosternon baini. Erythrosuchus, 

 when first described by me, was regarded as a Phytosaur. At that 

 time only a few bones of the skeleton had been discovered ; now the 

 skull and most of the skeleton are known. Huene has recently dis- 

 cussed the affinities at length, and forms for the type a new Order, 

 the Pelycosimia, believing it has affinities with the Pelycosaurs as 

 well as the Phytosaurs. In this I differ from him. Erytlirositchus 

 is, in my opinion, an ancestral Phytosaur not yet specialised for an 

 aquatic life, and related to the Belodon types in much the same way 

 as the Theropodous Dinosaurs are to the Sauropodous or the Creo- 

 donts to the Archgeoceti. Mesorhinus of Jaekel to some extent 

 forms a connecting link. 



Eunotosaurus of Seeley I have placed in the Chelonia. The skull 

 and limbs are still unknown, but the eight pairs of broad ribs and the 

 structure of the vertebrae seem to suggest that we have here an 

 ancestral Chelonian. Three specimens are known, all from the 

 Pareiasaurus zone or Middle Permian beds. 



ADDENDUM [see next page]. 



