304 Dr. C. W. Andrews on some new Steneosaurs 



Steneosaurus durohrivensis, sp. n. (PI. VIII. fig. 2.) 



A tliird species of Steneosaurus wliich occurs in the Leeds 

 Collection has a considerably shorter rostrum than those 

 just described, but at the same time it is longer than in 

 S. edwardsi, which is found in the same beds. It differs'from 

 the contemporary S. heberti in possessing only 33 teeth in 

 the upper jaw instead of 39-40 as in that species, and the 

 mandibular symphysis is relatively longer. The points of 

 difference from -S^. intermedins are the same. 



The type specimen (Leeds Coll. 18) upon which it is pro- 

 posed to found this species is a beautifully preserved and 

 nearly complete skeleton, including : — skull, mandible; 9 

 cervical, 14 dorsal, 2 sacral, and 39 caudal vertebras; many 

 ribs of both cervical and dorsal regions, several chevrons ; 

 shoulder-girdle, humeri, (?) radius and ulna; pelvic girdle 

 and most of the bones of the hind limb ; many scutes from 

 all regions of the body. In the present paper only the skull 

 and mandible will be briefly described, the complete account 

 being left for the ' Descriptive Catalogue of the Marine 

 Reptiles of the Oxford Clay ' now in preparation. 



In the skull the temporal fossag are very large and about 

 twice as long as wide. They are separated by a high and very 

 thin sagittal crest. The orbits are relatively rather smaller 

 than in S. leedsi and are more widely separated. The frontals 

 are almost smooth ; their anterior angle is a little in front of 

 the orbit ; the form of their anterior border will be best under- 

 stood from the figure (PI. VIII. fig. 2), and differs widely from 

 that of the frontals in S. leedsi and S. hebei-ti, but approaches 

 that figured by Bigot in S. intermedins. The nasals terminate 

 anteriorly opposite the 16th maxillary tooth, counting from 

 before backwards. In front of the orbit the rostrum narrows 

 rather quickly at first, then very gradually to the premaxillary 

 region, which is only a little expanded. The suture between 

 the premaxilla and maxilla is convex posteriorly on the upper 

 surface, the facial processes of the premaxilla extending back 

 to the level of the second maxillary tooth. On the palate the 

 suture between the two bones runs forward after crossing the 

 alveolar border, and an anterior prolongation of the maxillje 

 is thus interposed between the small palatal plates of the 

 premaxillse. The median suture between these latter is 

 interrupted by a foramen situated at the level of the socket 

 of the third tooth. 



