PELONEUSTES EVANSI. 



to 



the inner side of the teeth in use seems to show that the normal tooth-replacement was 

 in operation. 



The atlas and axis of this specimen, allowing for crushing and fracture, are similar to 

 the atlas and axis of the type specimen described and figured by Seeley in Quart. 

 Journ. Geol. Soc. vol. xxxiii. (1877) p. 716, figs. 1 & 2. The centra of the other 

 cervicals are also like that of the fourth cervical figured by Seeley. As in Peloneustes 

 philarchits, the length of the centrum in the mid-ventral line is greater than that of 

 the dorsal side. The neural arches are high ; the zygapophyses are strongly developed, 

 the articular surface of the anterior zygapophysis in most of the cervicals being gently 

 convex, the surface of the post-zygapophysis being correspondingly concave. The 

 neural spines seem to have increased in height from before backwards ; they differ 



Text-fig. 28. 



Teeth of Peloneustes evansi. (E. 389 L, ? s nat. size.) 

 W.8., surface of wear. 



widely in form from those of Peloneustes philarckus in that, instead of being com- 

 pressed from side to side, they are flattened from before backwards, particularly at 

 their upper ends, towards which they widen out ; the anterior face bears a number of 

 rough ridges, running from the base of the spine to the summit. This flattening 

 may have been produced in part by post-mortem pressure, but since it occurs on 

 the neural spines of all the cervicals, it was no doubt present in the living animal 

 and indicates that the movements of the neck were in some way different from 

 those habitual to Peloneustes philarchus ; the cervical ribs are similar to those of 

 that species. The dorsal centra are much crushed, but were perhaps rather shorter 



PART II. L 



