UPPER, OR FLINTY CHALK. 243 



reposes upon the flinty chalk, and contains beds of flints perfectly re- 

 sembling those of the chalk formation. 



The vertebrae represented in the figures above referred to, are from 

 the Upper chalk, near Lewes ; and being found in the same quarry, and 

 at a short distance from each other, may probably have belonged to the 

 same individual. Like those of the crocodile, motiitor, inguanas, and the' 

 greater part of the saurian animals, they have the body convex posteriorly, 

 and concave anteriorly ; a structure, that distinguishes them from those of 

 the cetacea, and fishes. 



The bone, fig. 13. Tab. xxxiii. appears to correspond most completely 

 with the posterior dorsal vertebrae in the spinal column of the Maestricht 

 monitor, figured by Faujas, PI. 52 ; particularly with the third and fourth 

 vertebrae, reckoning from the left hand of the specimen. The body of 

 the vertebra is rather compressed, about two inches long, and 1-4 inch 

 high; the face is sHghtly elliptical. The convexity of the posterior 

 extremity is but shght, and the concavity of the opposite side of a cor- 

 responding depth, the surface being perfectly plain and smooth. The 

 spinous process, of which a fragment only reiuains, is compressed, and 

 occupies the anterior four-fifths of the body of the vertebra. 



The specimen fig. 3. Tab. xU. contains two vertebrae articulated to 

 each other. They are shorter than the one above described, and each 

 has an inferior apophysis. In their general characters, they resemble the 

 vertebrae delineated in PL vii. and viii. of Faujas; their bodies are 

 compressed, and their length and height nearly equal ; their faces are 

 eUiptical in a vertical direction, the transverse diameter being 1"1 inch, 

 and the longitudinal 1*5 inch. The dorsal apophyses are narrower than in 

 the preceding example. The inferior apophysis is strong, and rounded at 

 the base, and suddenly contracts into a spinous process, which when entire, 

 was probably several inches in length. As this appendage is placed rather 

 laterally, it was suspected that another might exist on the opposite side, 

 and that the union of the two would form a triangular bone, corresponding 

 to the Vos en chevron of the crocodile, and other animals of the hzard tribe. 

 To ascertain this point, the chalk was removed so far as was practicable, 



I I 9. 



