58 FOSSIL REPTILIA OF THE LONDON CLAY. 



Serpents, is that low, tuberous angle at the corresponding part of the vertebra of the 

 Eryx (fig. 21). The posterior zygapophysis resembles, of course, the anterior one in 

 its much less extent, especially transversely, as compared with that in the Python, and 

 the posterior border of the neurapophysis (fig. 5, z, n) rises from its apex vertically, 

 or a little inclined outwards and backwards, giving a squarish form to the surface of 

 the neural arch in which the zygantra (za, fig. 7) are excavated ; these cavities, in 

 proportion to the articular ball beneath, are smaller and less deep than in the Python, 

 or any other existing genus of Serpent. The sloping sides of the neural arch above 

 the zygapophysial ridge are more concave than in Python, and so resemble those parts 

 in Coluber and Ilydrus. The latter genus (fig. 25) and Crotalus (fig. 9) most resemble 

 Palaop/tis in the proportions of the neural spine (ns) ; this part, however, in Palceophis 

 differs from that of Ilydrus in having its base coextensive with the supporting arch, 

 springing up from the fore part of the zygosphene, whilst this part entirely projects 

 forwards, clear of the base of the spine in Hydrus, as in Python, Coluber, and Naja ; 

 but in Crotalus the base of the spine has the same antero-posterior extent as in 

 Palaophis, and it comes very near to the fore part of the zygosphene in Eryx. The 

 neural spine has been more or less fractured in every specimen of the brittle crumbling 

 vertebrae of the Palaop/tis Typ/icsus from the Bracklesham Clay ; only one specimen, 

 which I carefully worked out in relief from a mass of matrix, after imparting some of 

 its original tenacity to the substance of the bone, affords a true idea of the peculiar 

 character of these Ophidian vertebrae, which is afforded by the great height of the 

 neural spine (see T. XIV, fig. 27, ns) ; but even here, although the fore part of the spine 

 equals in vertical extent that of the rest of the vertebra beneath it, I am not sure that its 

 entire extent is preserved, the part having been obliquely broken away behind this 

 point before the specimen came into my hands. Some vertebrae of another species of 

 PalcBophis from Sheppy, show this elevated spine to be a generic characteristic of the 

 fossil vertebrae. 



The ent:'~e vertical extent of the vertebra, fig. 27, from the end 



of the hypapophysis to the summit of tne neural spine is 

 The length of the same vertebra is .... 



The length of a larger vertebra of the same species 

 The length of the smallest free vertebra .... 



Inches. Lines. 



2 5 



1 2 



1 4 



5 



I have specified this last vertebra as being ' free,' because in Mr. Dixon's collection, 

 by far the richest in the remains of the great Palceophis of Bracklesham, there are two 

 smaller vertebrae anchylosed together by both their bodies and neural arches (T. XIV, 

 figs. 32, 33, 34), which, therefore, are not c atlas and axis,' but from their compressed 

 form I should judge rather to have come from the opposite end of the vertebral 

 column : they have not formed, however, the very extremity of the tail, like the 

 terminal anchylosed vertebrae in the Boa constrictor, or those supporting the rattle 



