204 



DR. B. PETRONIEVIOS ON THE LOWER JAAVS OF THE 



when text-fig. 4 is compared with text-fig. 5. So that, although the 

 hind end of the dentary in Cynognathus goes farther back on the 

 inner than on the outer side, it is clear from this comparison that it 

 did not reach the squamosal and that the possibility of an incipient 

 condyle of the dentary in Cynognathus is excluded. 



Text-figure 8. 



arts f dent ? 

 i 



GompJiognatlms : articular surface of the left squamosal. Nat. size. 

 art. ; articular. 



a rt.sf.de nt ? ; probable articular surface of dentary. 

 art.srf qu. ; articular sur.ace of left quadrate. 

 dent. ; dentary. 



The inner ,£fde of the jaws shows the same hones in both 

 cases (comp. text-fig. 3 with text-fig. 6). The comparison shows 

 that the splenial goes farther back in Gomphognathus than in 

 Cynognathus. 



The essential difference above mentioned that exists in respect 

 to the relation of the articular bones and the hind end of the 

 dentary to the squamosal between the Gornphognathus-skuW of our 

 specimen and the other specimens known under the names of 

 Gomphognathus and Diademodon (a general survey of which has 

 been given by Watson, 1911, p. 327 seq.) suggests the well- 

 founded supposition that our specimen is genericaily different 

 from all the other specimens of the same kind, which are all 

 essentially similar in the above point. Beyond that, a comparison 

 between the lower jaw of Gomphog nathus kannemeyeri (figured 

 by fSeeley (1) 1895, tig. 2, p. 8) and of Diademodon mastacus 

 (figured by Broom, 1905, fig. 1, pi. x.) shows that they are similar 

 in shape, while the shape of the lower jaw of our specimen 

 (comp. text-fig. 2),especia,ll}^ the shape of its coronoid process, is very 

 different. So that I agree with Watson in his identification of 

 Gomphognathus and Diademodon for all the other sj>ecimens 



