Manchester Mcuioirs, Vol. Iv. (191 1), No. 18. 



XVIII. Notes on some British Mesozoic Crocodiles 



By D. M. S. Watson, M.Sc. 



Read December i^th. igio. Receii'ed for pitblication Janua)-y 2-^th. igii. 



I. Steneosaurns stepJiani, Hulke. 



The under surface of the skull was not described by 

 Hulke in his description of this species ; it has recently 

 been further developed, and now shews some interesting 

 features. 



The basi-occipital shews the usual single condyle for 

 the atlas ; it is unusually short and flattened. The two 

 lateral processes for muscular attachments are small in 

 proportion to the great size of the skull ; they are 

 separated by the pit in which lies the opening of the 

 median eustachian tube. The grooves at the junction of 

 the basi-occipital and basi-sphenoid, which lodged the 

 canals leading from the lateral to the median opening of 

 the eustachian tubes, are well marked. 



The basi-sphenoid is only exposed on the ventral 

 surface for a short antero-posterior space : it is as usual 

 divided by a median ridge, with a wide flat surface, 

 which separates the grooves leading down and round to 

 the underside of the quadrate, the meaning of which is 

 still obscure. S. stephani is unusual in that these grooves 

 are entirely directed laterally. 



Very little of the pterygoid remains. Only a small 

 area some 4cms. long behind the posterior nares is repre- 

 sented by actual bone ; but the impression of the right 

 pterygoid and ecto-pterygoid gives a good idea of what 



May 2gth, igii 



