﻿FOREST-MARBLE. 



21 



§ 2. BOTHRIOSPONDYLUS FROM THE FOREST-MARBLE. 



Species — Bothriospondylus robustus, Ow. Plate VI. 



Of the two extinct Crocodilians from the Oolitic deposits (probably corresponding 

 with the Oxford Clay) in the vicinity of Honfleur and Havre, of which the jaws and 

 teeth are figured in PL VIII of the 2nd Part of the fifth volume of Cuvier's ' Ossemens 

 Fossiles,' 4to, 1824, one in which the fore-part of the centrum was convex and the hind- 

 part concave, and to which H. v. Meyer afterwards attached the generic name 

 Streptospondylus, was also characterised by lateral depressions (torn, cit., PI. VIII, 

 fig. 13). 1 I have figured a vertebra of this type, from the Lias of Whitby, under the 

 name of Streptospondylus Cuvieri. Assuming the accuracy of the ascription of this type 

 of vertebra to the associated jaws and teeth at Honfleur, the genus Streptospondylus 

 is a crocodilian one, and the sacrum would accord with the characters of the order. 



I have long had or known evidences of the Reptilian genus characterised by the 

 deep and elongated lateral depressions of the centrum undermining the piers or plates 

 supporting the neural arch. But not until the acquisition from the Kimmeridge Clay of 

 the above-described elements of sacral vertebras, similarly excavated, were grounds 

 afforded for the determination of the order or group of Saurians to which the Bothrio- 

 spondylus belonged. 



The earliest indications of the genus were afforded by fragmentary vertebras or 

 vertebral centrums from the Forest-marble of Wiltshire, of which the least mutilated is 

 figured in PI. VI. 



It is from the same or contiguous region of the spine as the subjects of PI. V. 

 The degree of convexity of the anterior surface (PL VI, fig. 1, a) is the same as that in 

 the subject of fig. 1, PL V, a . The posterior concavity also shows the irregular tract 

 at the centre, b, as in that of Bothriospondylus suffossus (Plate V, fig. 3). 



The lateral fossa (PL VI, fig. 1, /), with the same relative longitudinal extent, is some- 

 what less deep. 



The whole centrum is shorter in proportion to its height and breadth than in the 

 subject of PL V, fig. 1 ; it has come not merely from a larger individual of the species, 

 but from another species of the genus, with seemingly a relatively larger, less elongate 

 trunk. This vertebra repeats the textural character of the genus in the unossified 

 proportions of the centrum, causing the large cancelli (PL VI, fig. 2) into which spar 

 has infiltrated and crystallised in the fossil. I regard, therefore, the vertebras from the 

 Wiltshire Oolitic or Mesozoic deposits called ' Forest-marble ' as indicative of a species 



1 " Perriere la facette, qui recoit la tete de la cote, est une fosse profonde." Cuvier, torn, cit., p. 155. 



