the Skull of Diaderaodon. 327 



the brain-case, l)eing represented by the process which I 

 have dcscril)eil above in Diailemodon. 



The evidence on which he seems to rely is that in Dieyno- 

 donts, Dcinoccphalians, and Droniasaiiria the side of the 

 Ijrain-case is overlappoil by processes of the squamosals and 

 postorbitals or postfrontals, which meet and exclude the 

 parietal from the tem|)oral fossa. In Dicynodonts and 

 sjme Deinocephulians I have been able to see this arrange- 

 ment, l)ut even in these cases there is still a squamoso- 

 postorbital arcade. It appears to me simpler to regard the 

 condition in Dicynodonts, &c., as secondarily arrived at from 

 one resembling that in Cynodonts. 



The occurrence in the type skull of Cynognathus crater o~ 

 not us of a small infra-temporal fossa lying between the jugal 

 and the squamosal appears to be conclusive evidence that 

 the temporal fossa of Thera|)sids does not represent the 

 iufra-temporal fossa of Diapsids. 



This small infra-temporal fossa in Cynognathus was 

 correctly interpreted by Seeley. 



Systematic Revision of the Gomphognathid Genera Diade- 

 modon, Gomphoguathus, and Diastcmodon. 



In 1894< Seeley founded the genus Diadeniodon for some 

 frag-nents of jaws from the Karroo which showed molar 

 teeth with wide flat crowns ornamented with cusps and 

 ridges. The type species is Diadeniodon tetragonus, founded 

 on a small piece of snout, and to the genus were referred 

 D. braclujtiura, the type specimens being isolated teeth; 

 D. mastacus, founded on a piece of maxilla with three 

 perfect teeth ; and D. broivni, founded on the middle portion 

 of a skull with one perfect tooth. 



In 1895 Seeley founded another genus, Gomphognathus, 

 distinguished from Diadeniodon by the cheek-teeth being 

 worn down flat. 



The type species, G. kannemeyeri, was founded on a 

 mandible j-howing the teeth, to which was attached the back 

 of a skull and some cervical vertebrae. To this genus Seeley 

 referred an excellent skull lacking the lower jaw, which is 

 the type of G. polyphagus, and another excellent skull with 

 the mandible closed on the palate, which he referred to the 

 same species. 



More I'ecently Seeley described a new species, Diademodon 

 entoniophonus, the type being the middle portion of a skull 

 with some teeth. 



Finallv, in October 1908, Seelev described a new subgenus 



22* 



