196 MARINE EEPT1LES OF THE OXFORD OLAY. 



B. 3540 (Leeds Coll. 140). Imperfect skull (PL XI. fig. 1) wanting the premaxillse and the jugal 

 arch ; the whole is much crushed from above downwards, so that, as usual, the palate is 

 almost entirely destroyed. Type specimen. 



The dimensions (in centimetres) of this specimen are : — 



Length from occipital surface to tip of maxillae 51*7 



„ „ ,, nasals 35 - 5 



Length of nasals 2O0 



Distance between nasals and premaxillae 8'5 



Width between outer angles of quadi-ates 17'8 



Least width Detween orbits 9 - 5 



Width between outer aagles of prefrontals 14*6 



Length of the frontal anterior to temporal fossae 9-3 



E. 3899. Imperfect skull wanting the premaxillae and jugal arch : much crushed from above 

 downwards. 



The dimensions (in centimetres) of this specimen are : — 



Length from occipital surface to tip of maxillae . (approx.) 52-0 



„ to tip of nasals 34 - 8 



„ of nasals 19 - 4 



Distance between nasals and premaxillae .... (approx.) 1O0 



Width between outer angles of quadrates 18 - 



Least width between orbits 7"7 



Width between outer angles of prefrontals 13 - 8 



Length of the frontal anterior to temporal fossa; 8*5 



Metriorhynchus cultridens, n. sp. 



[PI. XI. figs. 2-4 ; text-figs. 60, 61 B, C, 66, 73 E.] 



Type Specimen. — A skull and mandible (PI. XI. figs. 2, 3; text-fig. 60, 73 E), teeth 

 (PI. XI. figs. 4, 4 a, 4 b, 4 c), atlas and axis (text-figs. 61 B, C), four other 

 cervicals, sixteen dorsals, two sacrals and thirty-seven caudals (text-fig. 66), numerous 

 ribs, chevrons, ilium, iscbia, pubes, femora, and odd bones of hind foot. (R. 3804, 

 Leeds Coll. 170.) 



This species has been founded for a type of Metriorhynchus in which the rostrum is 

 comparatively short, though the shortening is not carried so far as in M. brachy- 

 rhynchus, and the nasals are separated from the premaxillae by an interval equal to 

 about a quarter of their own length. The supraorbital notch forms a very open 

 continuous curve ; the frontals bear a slightly developed sculpture of irregular grooves, 

 which are much more strongly developed on the prefrontals. The teeth (PI. XL fig. 4) 

 are strongly compressed, with long, relatively slender, and almost completely smooth 



