48 Messrs. Embleton and Atthey on the 



behind the last-named tusk, another, which has a diameter 

 of only \ inch ; and behind this is a depression much larger 

 than the tusk itself. 



The third piece, indistinctly divided from the second, is 

 bounded laterally by the alveolar border and the malar ex- 

 ternally and the palate and ectopterygoid internally ; and its 

 posterior extremity forms a small portion of the anterior 

 boundary of the zygomatic arch. 



The palate-bones are long and rather broad, occupying a 

 large space on each side of the median line ; together they 

 have an ovate-lanceolate form, pointed in front and inclosed on 

 each side 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 connect- 

 ing suture can be made out. 



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

 have been found united by suture along the whole of their 

 inner edges j as it is, they have, as before mentioned, been dis- 

 located from the lower edge of the vomer and presphenoid for 

 a considerable distance along the median line, and can be 

 observed 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 \ inch apart, probably belonging to the basisphe- 

 noid ; they are sharply defined 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 

 immediately 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 of 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 other Reptilia) for articulation with the 



