OPHLDIA. 



Genus — Paleryx. 



The vertebrae of this extinct genus of Serpent (T.XIII, figs. 29-32, and figs. 37-38) 

 differ from those of Palceophis, in the absence of the pointed aliform production of the 

 hinder border of the neurapophyses, that border (fig. 29, ri) descending from the neural 

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

 The neural spine ins) 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, Crotahs, 

 and Hydrus ; in this character Paleryx resembles Eryx, Python, Boa, and Paleeophis. 

 The middle and posterior trunk-vertebras of Paleryx differ from those of Python and 

 Boa, and resemble those of Eryx 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 Eryx ; 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 Palaophis. 



Paleryx rhombifer. Tab. XIII, figs. 29-32. 



In the vertebras 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 (d) 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, PL 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. Tab. XIII, figs. 37 and 38. 



The smaller Ophidian vertebras, 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 



