On some Gorgonopsian Skulls. 515 



nopsian form with an undoubted vomer on the palate. The evidence 

 presented is thus contradictory, and it becomes necessary to examine 

 it in detail. 



In Gorgono-ps torv-us the anterior part of the median interpterygoid 

 suture is "open, with a visible strip of matrix in it". But it suddenly 

 ends and is with certainty not continued back in the middle line, 

 being apparently replaced by a pair of much less obvious sutures. 

 All the sutures on the palate other than those surrounding the median 

 vomer are obvious. 



The median bone in Scymnognathus whaitsi is shown in Watson's 

 figure in its posterior half only. It is said to correspond exactly in 

 position and relations with the posterior median bone in Gorffonops 

 and the back of the vomer in l)tdemodon. Watson, however, does 

 not definitely dissociate this bone from the one forming the inter- 

 choanal bar although he consideis them to be probablv distinct. 



Arctognathus curvimola is also said to show a median voiner. In 

 this form "there is no trace of a suture down the midline of the 

 groove, and its roof set-ins to be formed hv a median bone, which 

 terminates at the sudden end of the groove and must be bounded 

 by sutures with the pterygoids along its edges: of these presumed 

 sutures nothing can be seen" in the tvpe. 



It must be admitted that this evidence is somewhat unsatisfactory. 

 No stress can be laid upon the absence of a median suture, as in 

 some of the South African Museum specimens this suture is not 

 seen even though, as in the case of Grorgonognathus, the other 

 sutures of the palate are quite clearly marked. Both in ventral 

 aspect and in cross-section there seems to be evidence that the 

 pterygoids have become thoroughly fused together. ()u the other 

 hand the median suture is quite definitely present throughout the 

 entire distance between the interchoanal bar and the median ptery- 

 goid in Sycosaurus\ and. in consequence, until more definite proof 

 is given of its presence, I am unable to accept the vomer as for- 

 ming an integral part of the Gorgonopsian palate. 



In this connection it is of interest to note that in a Cynodont 

 skull from near Burghersdorp, recently described as Cynidiognctthus 

 (Trans. R. Soc. S. Afric. 19^2) it is only the front part of the 

 grooved portion of the palate which is formed by a median bone, 

 the hinder portion being made up of the pterygoids only. The 

 median bone here seems to be the same bone which further for- 

 ward forms the median septum of the skull and which is probably 

 the fused prevomers of the Therocephalia and Gorgonopsia. Notice 

 was made in that paper, with his permission, of a recent discovery 



