On Some Points In the Structure of the Dlcynodont Skull. 349 



near the middle line. From the sides of this sphenoidal portion of 

 the pterygoids there passes outwards and backwards a flattened 

 process which extends to and articulates with the quadrate. 



There is still a little uncertainty as to the structure of the 

 epipterygoid, and the skull of Oudenodon kolbei does not reveal the 

 structure satisfactorily on either side. What appears to he the 

 condition from other specimens is as follows : There is a long 

 slender rod-like epipterygoid or columella cranii which passes from 

 the parietal above to the pterygoid below. At its lower end it has 

 an antero-posterior development which is closely articulated with 

 the side of the basisphenoid and rests on the side of the pterygoid. 

 In front it passes forwards nearly to the palatine, and behind a 

 considerable distance towards the quadrate. 



The basisphenoid is a well-developed median bone situated 

 between the pterygoid in front and below, and the periotic and the 

 basioccipital behind. The anterior portion passes forwards above 

 the pterygoids and articulates with the vomer. The posterior and 

 middle part forms a considerable part of the strong bony framework 

 which supports the brain. In this bony mass sutures are not usually 

 distinct, but some can be made out with certainty and others with 

 much probability. Laterally and posteriorly the basisphenoid 

 articulates with the large bone which holds the ear capsule and 

 which may be called the periotic. Between the two is a foramen 

 for the Vllth nerve. On the undersurface the basisphenoid has 

 two flattened processes which form anterior supports to the 

 basioccipital processes. 



The periotic is a large massive bone, and it may possibly be made 

 up of an anterior prootic and a posterior opisthotic as in Ophthalmo- 

 saurus, but at present this is uncertain. It has a descending pro- 

 cess which forms part of the basioccipital process and in it is 

 the fenestra ovalis. 



The basioccipital is relatively small. It forms the lower third of 

 the occipital condyle and the greater part of the basioccipital pro- 

 cesses. By the side of the condyle is a large foramen for the IXth, 

 Xth, Xlth, and Xllth nerves. 



The exoccipital forms the outer third of the condyle and the 

 large lateral process of the occiput. 



The supraoccipital forms most of the upper flat portion of the 

 occiput. In the Oudenodon kolbei skull the structure of the occiput 

 is not very clearly shown, but the whole structure is known from 

 other specimens. 



In front in the middle line there is another bone which has not 



