118 M ABUSE EEPT1LES OF THE OXFOED CLAY. 



outline ; some of their edges show clearly that they united in suture with the 

 adjoining plates, while others are hevelled off as if to allow of the overlap of the 

 adjoining plate : their actual arrangement is quite uncertain. 



With a few skeletons some irregular rod-like, occasionally bifurcating, and 

 apparently imperfectly ossified bones occur, and in some cases may fuse with one 

 another : these are perhaps ventral ribs. 



Steneosaurus leedsi, Andrews. 



[Plate V.; text-figs. 34, A, B, 35, A, B, 36, 38, D,E,F, 40, 41, B, 43-47, 48, 49.] 



1896. "Steneosaurus roissyi, Deslongchamps," Bigot, Bull. Soc. geol. de Normandie, vol. xvii. p. 23, 



pi. ii. fig. 1. 

 1909. Steneosaurus leedsi, Andrews, Ann. Mag. Nat. Hist. [8] vol. iii. p. 300, pi. viii. fig. 1. 

 1909. Stenosaurus teleosauroldes, Auer, Palajontographica, vol. lv. p. 266. 



Type Specimen. — A nearly complete skull and mandible (R. 3320) described and 

 figured in Ann. Mag. Nat. Hist. [8] vol. iii. (1909) p. 300, pi. viii. fig. 1 (see also 

 PL V.). 



In 1896 Professor Bigot described a Steneosaur with a long and slender snout, from 

 the Callovian of Calvados. This he referred to Deslongchamps' Steneosaurus roissyi, a 

 name applied to some portions of a mandible from the Oxford Clay of Vaches Noires. 

 Mr. Leeds, however, has pointed out to me that these fragments are clearly portions 

 of a jaw of Metriorhynchus. Professor Bigot's specimen is almost certainly referable 

 to St. leedsi, described by me in March 1909 from a skull (R. 3320) in the Leeds 

 Collection. 



This species is especially characterised by the great length and slenderness of the 

 rostral portion of the skull and mandible. In a skull (PI. V. figs. 1-3) with a total 

 length of 81 cm., the length in front of the orbit is 59 cm., or about 73 per cent, of the 

 whole ; in St. hulkei the proportion is under 60 per cent., and in St. durobrivensis 

 about 61 per cent. The frontals terminate anteriorly in an acute angle. The anterior 

 angle of the nasals is about opposite the twenty-first maxillary tooth, and they are 

 thus separated by a long interval from the facial processes of the premaxillae, which 

 extend back to the level of the third maxillary tooth. There are 45-46 teeth on each 

 side of the upper jaw, four being borne by each of the premaxillse, the posterior two 

 being enlarged. The teeth are slender and sharp-pointed ; they are slightly com- 

 pressed at the extreme tip and the enamel is marked by a series of fine longitudinal 

 ridges. 



In the mandible (PL V. fig. 3) the symphysial portion is very long and slender, 

 occupying about 58 per cent, of the total length. There are 43-44 teeth on either 

 side of the jaw: of these about thirty-three are in the symphysial portion; the 

 splenials extend into the symphysis to about the level of the twenty-fourth tooth. 



In the account of the skeleton in the genus, reference has been made to the fact 



