THE iMOST PRIMITIVE- KNOWN REPTILE. 



Text-figure 6. 



275 



D. 



Cor I^^-'>Den. 



5. 



Den. 



"''''" CorI 

 5up,flN(;^ 



CoR.I. PalTh CorII. CorI 



5r 



PoST.Sp Pr.Rrt. f\N^. ^' 



Seymouria hayloriensis Broili.— Eight 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 lu 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 probably 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; Aet., articular; CoK. 1, II, III, the 1st 2nd 

 and 3rd coronoids; Den., dentary ; Post.Sp., post-splenial ; Pe.Aet' pre- 

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

 theiv position with the mouth closed ; Sp., splenial ; Sur.Ang., surangular 



