Structure of the T/ierocephalian SkuU. G7 



tlie exoccipltalg. Its upper border is connecfed by j;i,:?i?ed 

 suture witii the interparietal and its lateral borders are over- 

 lapped by the tabuhues. 



Fig. 2. 

 T.O. ?RK (.Far. 



Op.a B.Oc. FoRHflq. RstTem. 



f05&. 



The same skull as figure 1. Posterior aspect, x f . 



Reference-figures as in fig. 1, with, in addition :— I.Par., interparietal ; 

 Par., parietal; P.O., postorbital ; Sup.Oc, supra-occipital; Tab., 

 tabulare. 



The interparietal appears as a thin bone entirely on the 

 back o£ the .skull, whose lower border joins the .supraoccipital ; 

 the sides of the bone are overlapped by the tabulares and the 

 top of the bone overlaps the parietals. 



The tabulare is a thin bone overlappini^ the interparietal 

 and supraoccipital and covering some of the back of the 

 internal ramus of the squamosal. The lower end of the 

 bone thickens and passes round the outer end of the post- 

 ternporal fossa to meet the end of the opisthotic. The lateral 

 borders of the bones are removed by weathering in this 

 specimen. 



The opisthotic is a bone which articulates by straio-ht 

 smooth sutures with the basioccipital below and the ex- 

 occipital behind. It forms the posterior part of the pit, in 

 which lies the fenestra ovale, and the outer side of the 

 foramen jugulare. There is a powerful parocci[)itaI process 

 which forms the lower border of the post-temporal fossa and 

 articulates with the squamosal and tabulare distally. 



5* 



