316 ^Ir. D. M. S. Watson on 



pituitary fossa is well shown ; it lias a vertical surface nearly 

 a centimetre square ; and broken triangular areas show the 

 former presence of posterior clinoid processes. The posterior 

 wall of the fossa is not pierced by any openings, so that the 

 carotids must have entered it by passing along the sides of 

 the basisphenoid. 



Below the fossa is a large broken area, whence the basi- 

 sphenoid was once continued to form its floor. 



Prof. Seeley correctly identified the pit as the foramen 

 jugulare and the fenestra vestibuli of this specimen, but I 

 cannot accept the rest of his description of the bones of the 

 brain-case. 



Cynognathus crateronotus, Seele3\ 

 A re-examination of the skull of the type specimen shows 

 that the whole structure agrees very closely in all essential 

 details with that of the Diademodon skull. Many of the 

 sutures of the brain-case are visible and give further support 

 to those described in the latter genus. The system of 

 grooves over the brain-case is exactly as in Diademodon, but 

 the laminae covering them have been largely destroyed 

 during the development of the specimen. 



In two particulars the skull adds to our present know- 

 ledge : — 



1. There is a somewhat faint but quite definite jagged 

 suture crossing the triangular area on the underside of the 

 basisphenoid. This suture is quite unlike the straigiit 

 suture which one expects between two cartilage bones, such 

 as the basioccipital and the basisphenoid, and has much 

 more resemblance to the overlap of a membrane bone on to 

 a cartilage bone. 



It is probable that it is really the back of the vomer, 

 which would then have, as Broom has already pointed out, 

 all the relations of a mammalian vomer or of a reptilian 

 parasphenoid. 



2. The process of the squamosal which lies on the front 

 side of the occipital plate of the parietal is marked by 

 muscular insertions and impressions, which do not point 

 down into the temporal fossa, but backwards towards the 

 corner of the V separating the median from the lateral 

 regions of the occiput. 



The significance of this curious feature will be discussed 

 later. 



" Theromus." 

 The impression of the hinder part of a small skull which 

 Seeley found at Klipfontein and described as Theromus ? is 



