THE MOST PRIMITIVE KNOWN REPTILE. 



275 



Text-figure 6. 



D. 



COR.l. N rf~ / jV'DEN. 



Den. 



CoR.n 



CorI. 



SurAnq 



Cor.I. PalTh CorH. CorI. 



Sr 



Post.Sr FkfW. Kn^. 



Seymouria bayloriem 



Broili. — Right ramus of the lower jaw of my 

 skeleton, X 1. 



A. Inner surface. The area covered with parallel oblique lines is covered with 



matrix ; the teeth in the dentary are restored on the evidence of fragments of 

 that bone of a youug individual. The articular is drawn from that of a 

 young individual and is probahly slightly too small. 



B. Ventral view of a horizontal fracture passing just above the cavity of the lower 



jaw of my skeleton. 



C. Vertical section seen on the broken posterior end of the jaw. 



D. Vertical section seen on a fracture through the splenial region. 



Reference letters : — Ang-., angular; Art., articular; Cor. I, II, III, the 1st, 2nd, 

 and 3rd coronoids; Den., dentary ; Post.Sp., post-splenial ; Pr.Art., pre- 

 articular; Pal.Th., the palatine tusks, represented in dotted lines to show 

 their position with the mouth closed ; Sp., splenial ; Sur.Angl, surangular. 



