402 BRITISH FOSSIL REPTILES. 



In the present specimen tlie parapophysis is still developed from the side of the 

 centrum and from its anterior half; but it expands more rapidly as it approaches the 

 terminal ball, with which its own articular surface seems to be continuous. The side 

 of the centrum behind the parapophysis is convex vertically at its upper half, slightly 

 concave vertically as it descends to the thick inferior convex ridge, which is broadest 

 behind, as in the more advanced and longer vertebrae. 



The diapophysis is now supported by a thick, rounded prominence, beginning near 

 the lower and hinder part of the neural arch, and, expanding as it rises, it advances 

 to the base of the diapophysis ; this is the beginning or rudiment of the hinder 

 converging ridge in the type vertebra of Streptospondylus, as described and figured by 

 Cuvier.* 



The neural canal has the same shape and relative size as in the more 

 advanced vertebra (PL 31, figs. 1, 2, and 3). The pedicles or bases of the neural 

 arch present the same superior thickness, as compared with the Iguanodon, showing a 

 convex, rounded border behind as well as in front. There is a median depression at 

 the back part of the base of the neural spine. 



The following are admeasurements of the bodies of the above-described three 

 cervical and anterior dorsal vertebrae of the Wealden Streptospondijlus : 



Tilgate. Culver Cliff. Brook Point. Dorsal. 

 Inch. Lines. Inch. Lines. Inch. Lines. Lich. Lines. 



Transverse diameter of posterior concave articular 



surface . . . . .50606056 



Vertical diameter of posterior concave articular 



surface ..... 



Antero-posterior diameter of entire vertebra 

 Transverse diameter of the body across the par- 



apophyses ..... 

 Height from lower surface of centrum to the hind 



part of base of spine 

 Antero-posterior extent of parapophysis . 

 Interspace between upper and lower transverse 



processes ..... 



Jn the museum of the Geological Society of London there is a collection of rolled 



* Loc. cit. 



f It is evident that an inch at least, perhaps more, has been chiselled away from the ball which 

 terminated the anterior end of the body of this specimen in Mr. SauU's collection. 



