ON MAMMAL-LIKE REPTILES. 225 



17. On the Gorgonopsia, a Suborder of the Mammal-like 

 Reptiles. Bj R. Bkoom, M.D., D.Sc, C.M.Z.S. 



[Received December 31, 1912 : Read February 18, 1913.] 



(Plates XXXVI. & XXXYII.*) 



Index. Page 



Gorgonopsia, Affinities of the 229 



Scylacops capensis 226 



Scynmognatlms tigriceps 227 



When Gorgonops torvus was described by Owen in 1876 he 

 regarded it as the type of a distinct group, partly on account 

 of the apparent peculiarity of the nose, and also because the 

 temporal region was believed to be roofed. Lydekker in 1890 

 and Seeley in 1895 both agreed that the temporal region was 

 roofed, and Seeley proposed the name Gorgonopsia as a distinct 

 order for the reception of Gorgonops. A re-examination of the 

 type in 1909 convinced me that though the parietal region is 

 wide, Gorgonops has temporal openings like the other Therapsida, 

 and the discovery by the Rev. J. H. Whaits of a nearly perfect 

 skull of Gorgonops torvus shows that my observation was correct. 



Still one has long had the feeling that Gorgonops differed 

 considerably from the typical Thei'ocephalians. For a time I 

 inclined to place it with Titanosuchus and others in the Dino- 

 cephalia. Later on I put it back among the Therocephalians. 

 Now the discovery of one or two perfect skulls shows that the 

 difference from the Therocephalians is sufficient to warrant 

 the re-establishment of Seeley 's group — the Gorgonopsia — as a 

 distinct suborder of the Therapsida. I am well aware that the 

 formation of so many new orders and suborders of reptiles as 

 have been made in recent years has been criticized ; but it seems 

 to me wiser to separate into distinct groups forms that are 

 manifestly distinct than to grotip into one order animals that 

 are markedly different ; and one can now say without any fear 

 of contradiction that Gorgonops differs from the typical Thero- 

 cephalians more tha,n does a Carnivore from a Marsupial. As 

 will be seen from the present paper, the skull in many ways 

 approaches more nearly to that of the Anomodont. 



Skull. 

 Though nearly perfect skulls are known of Gorgonops torvus 

 and Scymnognathus v;haitsi, in neither species can the sutures be 

 very clearly made out. The discovery by Mr. S. H. Haughton 

 of two fine skulls from the Cistecejihcdus zone, and of a good skull 

 obtained by the Rev. J. H. "Whaits from the Pareiasaurus zone, 

 gives us matei-ial which reveals practically every point in the 

 structure of the skull. 



* For explanation of the Plates see p. 230. 



