CYNODONT REPTILES GOMPHOONATHUS AND CYNOGNATHUS. 199 



and 4), whilst in Cynognathus the articular goes farther back 

 than the dentary * (and it does this more externally than internally 

 — comp. text-fig. 5 and text-fig. 6, in which the length of these 

 portions of the dentary bone is the same). 



3. In Gomphognathus the posterior edge of the dentary bone 

 covers externally the articular bones almost entirely (comp. text- 

 figs. 2 and 4), whilst in Cynognathus the hind part of the articular 

 bones is clearly visible and considerably external to the dentary 

 bone (text-fig. 5). 



Text-figure 2. 



Gomphognathus : right ramus of lower jaw, external view. X J. 

 Shaded part covered with matrix. 



dent. ; dentary. 



in.con.dent. ; incipient condyle of dentary. 

 pr.cor. ; coronoid process of dentary. 

 pr.ang. ; processus angularis. 



In connexion with the first point we must add that Seeley's 

 contention (comp. Seeley (1), 1895, p. 26), that the articular bones 

 of Gomphognathus were "somewhat displaced, being drawn away 

 laterally from the edge of the dentary bones," must be wholly 

 rejected, because the lateral distance of these bones from the 

 dentaries is exactly the same on both sides (comp. text-tig. 1), 

 and the bony connexion of the almost horizontally situated 

 reflected angular lamina, which is well preserved on the left side, 

 is such (comp. text-fig. 1) that no doubt about the naturalness of 

 its position can be entertained. The angular notch limited by 

 this lamina is a large one, and comparatively large, also, is the 

 notch lying iu front of it, between the dentary on the one side, 

 and angular and splenial on the other (comp. text-fig. 1 ; the hind 

 part of the splenial is preserved only on the right side). 

 In Cynognathus the reflected angular lamina, whose position is 

 almost a vertical one, is preserved only partially (comp. text-fig. 6 



* In Ci/nognathus plati/ceps the hind end of the dentary is more prolonged back- 

 wards than in Cynognathus crateronotus, but it did not reach the squamosal. 

 Comp. Seeley (2), 1895, tig. 29, p. 135, and Broom, 1904, text-fig. 100. p. 496. 



15* 



