4 Watson, Notes o?i some British Mesozoic Crocodiles. 



It is probable that the reduction of the pterygoids is 

 to be correlated with the enlargement of the temporal 

 muscles implied by the increase in size of the supra- 

 temporal fossae, for this enlargement would imply a 

 reduction of the pterygoidal muscles and hence of the 

 pterygoid and ecto-pterygoid : the fact that this reduction 

 increases regularly as time goes on shews that the 

 Steneosaurs can have given rise to no eu-suchian form, for 

 in all " procoelia " the pterygoidal muscles are greatly 

 developed at the expense of the temporals. 



2. MetriorhyncJnis cp. Jiastifer : from tJie Cora/lin?i of 

 Headington. 



Crocodilian remains other than isolated teeth are so 

 rare in the Corallian that some account of a large part of 

 the rostrum of a MctriorJiynchus from the Corallian, Lower 

 Calcareous Grit, of Quarry Field, Headington, may be 

 of interest. 



The specimen was obtained by Mr. Manning, and is now 

 in the Manchester Museum, number L. 6459. It consists 

 of a part of the snout including the tip of the frontal and 

 terminated anteriorly by a transverse fracture in front of 

 the nasals. So far as it goes it is quite perfect, being 

 uncrushed. The skull was mutilated before fossilisation, 

 the exposed edges being rounded. I do not consider that 

 this indicates derivation of the specimen from some older 

 bed but merely natural washing about on a beach. 



The specimen is remarkable for its great solidity, the 

 frontal being some 30mm. in thickness, and the pre-frontal 

 of similar substance. 



Viewed from above the specimen shews the maxillae 

 meeting one another in the middle line for some 5cms. 

 In this region they form an almost flat dorsal surface from 



