from the Oxford Clay of Peterborough. 307 



The mandible is very massively constructed. The sym- 

 physial region, which occupies about 42 per cent, oi^ the total 

 length, is flattened ventrally and lias a considerable anterior 

 expansion, which is greatest at the sockets of the third and 

 fourth teeth. 



The lower teeth are about 28 in number. The first two 

 are small, then follow two large teeth closely crowded together. 

 Behind these is a rather small tooth, and behind this point 

 the rest increase in size till near the hinder end of the series. 

 The most remaikable character of this dentition is that about 

 half the mandibular teeth bite into deep pit-like sockets in 

 the maxilla ; the outer walls of these pits form slight pro- 

 minences on the alveolar edges o£ the maxillee. If this 

 peculiarity of the dentition is normal it would probably 

 justify the establishment of a new genus for the reception of 

 this species, but there is some doubt whether it may not be 

 the result of great pressure, which has driven the points of 

 the lower teeth into the maxilla, while the bone was in 

 the clay in a semi-plastic condition. 



The individual teeth are thick, circular in section, and 

 have blunt points ; the enamel of the crown is raised into a 

 number of fine longitudinal ridges of varying length ; in 

 some of the teeth two or three ridges on opposite sides are 

 more strongly marked than the others and are continuous 

 from base to tip of the crown. 



This crocodile seems to have been a very powerfully built 

 animal, with jaws and teeth of greater strength than in the 

 other Steneosaurs. The hind limb was very long, the femur 

 alone measuring 45 cm. in length. A detailed account of 

 the skull and skeleton will bo given in the Catalogue above 

 referred to. 



The approximate measurements of the type skull and 

 mandible (R. 3168) of Steneosaurus ohtusidens are : — 



Skull. cm. 



Total length 116 



Preorbital length 71 



Width between outer angles of quadrates 37*5 



Length of temporal fossai (inner side) 33 



Width „ „ _„ (?)14 



„ of frontals between orbits 8'5 



„ of middle of snout 9 



„ at narrowest point behind premaxillary 



expansion 7'3 



,, of premaxillary expansion 9'o 



