208 DE. EMBLETON AND ME. ATTHEY ON THE 



for about an inch by the vomers, behind this by the palate-plates 

 of the maxillaries, and next by the ectopterygoids. Their 

 posterior ends abut upon the pterygoids ; but no connecting su- 

 ture can be made out. 



Had the skull not been so much crushed, these bones would, 

 probably, have been found united by suture along the whole of 

 their inner edges ; as it is, they have, as before mentioned, been 

 dislocated from the lower edge of the vomer and presphenoid for 

 a considerable distance along the median line, and can be ob- 

 served lying apart with their serrated edges well preserved, 

 whilst the presphenoid and vomer form the ridge already named 

 as projecting between them. 



At the posterior termination of this ridge two pits, one on 

 each side of the median line, mark the position of the posterior 

 nares. Behind these are two projections opposite to each other 

 and about half an inch apart, probably belonging to the basi- 

 sphenoid ; they are sharply denned posteriorly and internally, and 

 slope downwards on their anterior and external sides. A well- 

 defined smooth groove or channel runs along their bases on the 

 inner and posterior sides from before backwards and is soon lost. 

 A distinct suture follows this groove, lying on its outer edge. 

 The grooves seem adapted for vessels or nerves; or it may be 

 that they are vestiges of the lateral Eustachian tubes. 



A transverse suture connects the posterior end of the median 

 ridge before noticed to that part of the base of the skull imme- 

 diately behind, which appears to be the basisphenoid, as it 

 articulates, or is continuous posteriorly, with the apex of the 

 basioccipital. The basisphenoid is difficult of definition, owing 

 to the crushed state ef the skull. 



The basioccipital. This is the somewhat triangular piece, 

 which, by its forwardly placed apex, articulates with the basi- 

 sphenoid : its sides articulate with the quadrates ; and its base 

 is occupied by a deep cup-shaped cavity, in place of the convex 

 condyles found in the Eeptilia, for articulation with the body 

 of the first cervical vertebra. The surface of the bone in front 

 of the articular cavity is smooth and slightly convex ; its sides, 

 somewhat rough, are overlapped a little by the quadrate bones. 



