152 



MARINE REPTILES OF THE OXFORD CLAT. 



incomplete in this region. Behind the orbit the bone is widened by the presence of a 

 prominence on its upper border, by means of which it unites with the postfrontal. 

 Behind this it becomes round and narrows, terminating posteriorly in a point which 

 overlaps the anterior end of the quadrato-jugal, thus enclosing the lateral temporal 

 fossa below. 



The palatine region of the skull (PI. XII. fig. 2 ; test-fig. 58) is in nearly all cases 

 more or less completely destroyed by the crushing to which it has been subjected. In 

 two specimens, however, of II. brachyrhynchus (Leeds Coll. 164-165, K. 3699-3700), 

 this part of the skull is fairly well preserved and has been described in detail by Mr. E. 

 Thurlow Leeds (Quart. Journ. Geol. Soc. vol. lxiv. (1908) p. 345), upon whose work the 

 following account is for the most part founded, the same two skulls being described. 



Text-fig. 58. 



J - fifr. '°t-J- 



Semi-diagrammatic figure of the palatal surface of the skull of Metriorhynchvs bracJiyrhynchus ; 

 partly after E. Thurlow Leeds. (About ^ nat. size.) 

 boc, basioccipital ; bs., basisphenoid ; eu.m. , median eustachian opening; i.nar., internal narial opening; 

 j., jugal ; l.t.f., lateral temporal fossa ; mx., maxilla ; pal., palatine ; p-f>:, postfrontal ; pmx., premaxilla ; 

 pi., pterygoid ; q., quadrate ; q.j., quadrato-jugal ; s.o.v., suborbital vacuity ; t.p., transpalatine 

 (restored); v., vomer (parasphenoid) ; i, 2, 3, 4, these figures mark the levels at -which are taken the 

 sections shown with the corresponding numbers in the next figure (text-fig. 59). 



Other specimens in which the palate is fairly preserved are the skull of a large 

 individual referred to M. superciliosum (R. 3016) and that of a young specimen of 

 M. durobriven.se (R. 2618) in which the vomer (parasphenoid) is particularly well shown. 

 The palatines (pal.) unite in front with the maxillae in a suture which may be 

 nearly transverse (M. Irachyrhynchus), but usually forms a median point meeting its 

 fellow in the middle line, and a lateral process projecting beyond the last, from which 

 it is separated by a notch which marks the course of the deep groove described above 



