ON BRITISH FOSSIL REPTILES. 89 



downwards to above the middle of the costal depression. This depression is 

 vertically ovate, with a deeper oblique pit in the middle, 2 inches in the long 

 diameter, by 1 inch 6 lines across the broadest part. The texture of this 

 vertebra is coarsely cellular, except for about two lines at the margin, where 

 it is in very compact laminae. The anterior articular surface of the centrum 

 is slightly and irregularly convex, being nearly flat at the upper part. 



There is a slight deviation from the symmetrical figure in the whole of 

 this vertebral fragment. The body of the vertebra is much contracted in 

 the middle, and suddenly expands to form the terminal articular surface. 

 This character is likewise indicated by Cuvier in his Crocodile d' Honjleur* ; 

 thus the transverse diameter of the middle of the vertebral body, across which 

 the present fossil has been fractured, measures 2 inches 3 lines, Avhilst the 

 same diameter of the convex articular extremity is 4 inches. 



The corresponding diameters of one of the anterior dorsal vertebrae of the 

 Streptospondylus, described by Cuvier, are respectively 1 inch 7 lines, and 

 2 inches 6 lines; whence we may conjecture that the length of the entire 

 vertebra here described would have been 4 inches and a half. The ver- 

 tical diameter of the articular surface is 3 inches 9 lines. 



The non-articular surface of the vertebral body is smooth, except near the 

 articular extremity, where it is rather coarsely rugous. The inferior ridges 

 and tubercles have disappeared at the part of the vertebral column to which 

 the present vertebra has belonged. 



The osseous substance of the present fossil, like that of the bones of the 

 Streptospondylus from Honfleur, presents a deep chocolate brown hue, and 

 takes a bright polish. It is not completely mineralized ; the small cavities of 

 a great part of the diploe are empty, and not filled with seraitransparent cal- 

 careous spar, as in the Honfleur specimens. 



With the portion of the vertebra above described there was associated the 

 extremity of a spinous process, which gradually expands to a rough obtuse 

 quadrilateral summit. This spine is characterized by having a very rugged 

 and thick ridge, developed from the anterior and posterior surface of what may 

 be regarded as the ordinary spinous process, the sides of which are smooth, 

 except near the summit. Inches. Lines. 



The length of this fragment of spine is ^ . . . 3 8 



The transverse diameter of the base 9 



The transverse diameter of the summit of the apex 1 6 



Antero-posterior diameter of spine 1 3 



Ditto, including the ridges 1 10 



In the Crocodile a thin plate is continued from the anterior and posterior 

 edges of the thicker spinous processes ; but the Streptospondylus, if I am 

 correct in attributing this spinous process to that genus, presents an extreme 

 and peculiar development of this structure. 



A portion of a compressed, conical, hollow tooth, with a brown dense glis- 

 tening dentine, covered by smooth enamel, and resembling that of the Mega- 

 losaurits, was associated with the preceding vertebra. The length of this 

 fragment of tooth is 2 inches 4 lines, but both ends are wanting. The breadth 

 is 8 lines; the thickness 5 linesf . If it really belong to the Streptospondy- 

 lus, it confirms the view of the aflRnity of that genus to Megalosaurus, which 

 has been suggested by the characters of the vertebra. With the above frac- 

 tured vertebra and tooth there were likewise found, in the oolite at Chipping 



* " Le corj)s de cette vertcbre, ainsi que des siiivantes, est beaucoup plus rttrcci dans son 

 milieu que dans les Crocodiles connus." — Osseni. Foss. ed. 1824, torn. v. pt. 2. p. 156. 



t The teeth conjectured by Cuvier to belong to the Honfleur Streptospondylun are conical 

 and striated. 



