202 MARINE REPTILES OF THE OXFORD CLAY. 



ADDENDUM. 



The teeth of Peloneustes philarclius (PL IV. figs. 3—5) vary much in different parts 

 of the jaw (see pp. 42, 43, and 46). The larger teeth (PL IV. figs. 3, 5) have a high, 

 sharp-pointed, and somewhat curved crown, which is nearly circular in section. At 

 the base the enamel is raised into numerous fine ridges running towards the point, 

 but for the most part not reaching more than half-way ; only two of the strongest 

 ridges actually reach the tip. The ridges are more numerous on the inner (concave) 

 than on the outer (convex) side of the crown. The root is long, circular in section, 

 and narrowing towards its lower end : there is a large pulp-cavity. The smaller teeth 

 (PL IV. fig. 4) have a short, somewhat sharply curved crown with numerous strong 

 enamel-ridges all round. In the upper jaw there are six teeth in the premaxilla 

 and twenty-eight to thirty in the maxilla. In the lower jaw the number is about 

 forty, of which fourteen to sixteen are in the symphysial region. 



