PEL0NEUSTE3. 45 



the lateral ramus curves inwards and backwards, crossing the posterior ramus as a high 

 cristiform ridge, forming a prominent flange on its ventral face, and disappearing in 

 the hinder part of the border of the posterior interpterygoid openings (p.p.v.). 

 Behind these the pterygoids overlap the basioccipital and basisphenoid, and probably 

 meet in the middle line ; posteriorly they are produced back into strong processes, 

 which seem to have overlapped and probably united with the lower ends of the 

 lateral processes of the basioccipital. Behind these the posterior ramus becomes 

 compressed vertically and runs back to join the inner border of the quadrate. On the 

 upper surface of the pterygoid about opposite the middle of the posterior inter- 



Text-fig. 14. 



sang. art. 



aug. 



sril.sym. dsym. 



d. sum. . 



Mandibular ramus of Peloneustes ph.il archus (E. 3803, \ nat. size) : A, from outer side ; B, from inner side : 

 C, mandibular ramus of Murcenosaurus from inner side. (R. 2861, about ^ nat. size.) 



ang., angular : cor., coronoid ; d., dentary ; cl.sym., symphysis of dentaries ; g., dental groove ; 

 s.ang.art., the united surangular and articular bones ; spl., splenial ; spl.sym., symphysis of the splenials. 



pterygoid vacuity, is the surface of attachment for the epipterygoid (columella 

 cranii, col., PL IV. fig. 2), a rather large bone strongly compressed from side to side 

 and uniting with the pterygoid below and the parietal above. 



Mandible (text-fig. 14, A, B). — The Leeds Collection contains some nearly complete 

 specimens of the mandible of Peloneuates, and an examination of these shows that they 

 closely resemble the mandible of Pliosaurus and differ widely in structure from those 

 of the Elasmosaurs. In the first part of this Catalogue (p. 89) the description of the 

 mandible in these latter is in several respects inaccurate, and a correction of the 



