150 BRITISH FOSSIL REPTILES. 



spine to the posterior zygapophyses, with a convex curve as in most modem Serpents. 

 The neural spine {ns) is low, the antero-posterior extent of its truncated summit 

 exceeding the height. There is no point of bone extending outwards beyond the 

 articular surface of the anterior zygapophysis {z), as in Coluber, Viper a, Naja, Crotalus, 

 and Ilydrus ; in this character Paleri/x resembles Eri/x, Pi/tJton, Boa, and PalaopMs. 

 The middle and posterior'trunk-vertebrse of Paleryx differ from those of Pi/tJmi and 

 Boa, and resemble those of Eri/x in having a sharp and well-developed hypapophysial 

 ridge {h) coextensive with the under surface of the centrum, and deepest at its posterior 

 half ; but the border here is gently convex, not angular as in Eri/x ; and the posterior 

 border of the neurapophysis is less produced than in Eryx ; the articular cup and ball 

 are relatively larger, especially transversely ; the cup is a full transverse ellipse, not 

 circular as in Eryx ; in this respect it resembles that of Python and Palceophis. 



Paleryx rhombifer. Plate 2, figs. 29-32. 



In the vertebrae of this species the hypapophysial ridge {h) is sharp and well 

 produced ; the neural spine {ns) is rhomboid, not rounded off anteriorly ; the zygo- 

 sphene [zs, fig. 30) has the same relative vertical extent as in the Python. The 

 diapophysial tubercle id) is less elongated vertically than in Python and Boa^ 

 presenting proportions like those of the vertebra of the Eryx (fig. 22, d) ; the zygapo- 

 physes {zz) are more pointed at their terminations. The figures 29-32, PI. 2 represent 

 the largest of the trunk-vertebrae upon which has been founded the genus and species 

 above defined : they indicate a land Serpent of about four feet in length. They were 

 obtained from the Eocene sand at Hordwell by Alex. Pytts Falconer, Esq., of Christ- 

 church, Hants., to whose liberality I am indebted for the specimen figured. 



Paleryx depressus, Owen. Plate 2, figs. 37 and 38. 



The smaller Ophidian vertebrae, indicative of the above species, agree in their 

 generic characters with the foregoing ; that is to say, in the shape and development 

 of the hinder border of the neural arch in the relations of the diapophysis to the anterior 

 zygapophysis, in the shape and size of the articular cup and ball of the centrum, and 

 in the shape of the diapophysial, tubercle for the rib. But the whole vertebra is more 

 depressed ; the hypapophysial ridge is relatively thicker and less produced ; the 

 zygosphene has much less vertical thickness, and there is a corresponding modification 

 of the zygantra ; the neural spine is relatively lower and of a different shape, having 

 its anterior angle rounded off, and its posterior one more produced backwards. 



As I have failed to discover modifications of the kind and degree above described 

 in the dorsal or free rib-bearing vertebrse of the same species in any of the existing 

 genera of Serpents, I am left to interpret such characters as indicative of a distinct 



