200 MARINE EEPTILES OF THE OXFORD CLAT. 



nasals passes through the outer angles of the prefrontals. The supraorbital notch is 

 sharply angulated. The portion of the frontals between the temporal fossa? is broad 

 and flat ; in the parietal region the intertemporal bar narrows very rapidly. The pitted 

 sculpture is moderately well developed on the frontals, but is most marked on the 

 outer edge of the prefrontals. The teeth are about sixteen on each side in the upper 

 jaw and twelve to fourteen in the lower ; their crowns are compressed, and the anterior 

 and posterior carina? well marked ; the enamel is nearly smooth, there being only an 

 extremely fine sculpture of numerous longitudinal ridges. 



R. 1994. Symphysial portion of a mandible and some teeth. Type specimen described and figured 

 by Lydekker in Quart. Journ. Geol. Soc. vol. xlvi. (1890) p. 284, figs. 2 & 3. This 

 specimen seems to have undergone considerable compression from above downwards, so 

 that its width is exaggerated. There are twelve dental alveoli on the right side and 

 thirteen on the left. The splenials extend forwards to the level of the seventh tooth 

 on the left side. The length of the symphysis is about 21 cm., that of the alveolus- 

 bearing part of the dentary about 23 cm. 



E. 3321. An imperfect and much flattened skull of a large individual ; the premaxillary region is 

 wanting. A few teeth are preserved. 



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



Length in mid-dorsal line to hinder extremity of premaxillae . 42 p 4 



„ to anterior end of nasals 40"7 



„ of nasals 19"6 



Distance between nasals and premaxillae l - 8 



Least width between orbits 11*9 



Width between outer angles of prefrontals 22'9 



Length of the frontal anterior to the temporal fossae .... 10-9 



The measurements of width are too great, through the crushing that has been 

 undergone. 



£. 2039 (Leeds Coll. 8). An incomplete skull wanting the occipital, premaxillary, and palatine 

 regions ; also an imperfect left ramus of the mandible, which is strongly compressed 

 laterally, so that it differs widely in appearance from the type mandible (R. 1994), in 

 which the compression is vertical; the number of mandibular teeth is thirteen or 

 fourteen. 



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



Length of nasals 18'7 



Distance between nasals and premaxillae 2 - 5 



Least width between orbits 12 - 7 



Width between outer angles of prefrontals 22 - 9 



Length of the frontal anterior to the temporal fossae . . . . 11 - 2 



„ mandibular symphysis (approx.) 25-0 



