ON BRITISH FOSSIL RE>PTILES. 69 



In No. ^, Mantellian Collection, the bases of the neurapophysis remain 

 attached to the centrum, which presents the same characters as No. ~. On 

 the outside of the neurapophysis are two slightly developed broad obtuse 

 ridges, converging towards each other from the outer side of each angle or 

 end of the base of the neurapophysis ; the ridge corresponding with the pos- 

 terior of these in the Igtianodons vertebra rises more vertically, and is in 

 higher relief. 



The neurapophysial suture slightly undulates in its horizontal course, and 

 rises in the middle instead of descending upon the centrum, as in the Ple- 

 siosaurs. 



The present vertebra is alluded to at p. 70, and figured at pi. ix. fig. 11, of 

 Dr. Mantell's ' Illustrations of the Geology of Sussex,' as a lumbar vertebra 

 of the Megalosuurus. But in the ' Geology of the South-east of England,' 

 the accomplished author, speaking of this vertebra, observes, " It cannot, I 

 now think, be separated from those figured in the same plate, as belonging 

 to a crocodile." — p. 297. Fig. 8, pi. ix, (Tilgate Fossils) is, however, a 

 caudal vertebra of the Cetiosanrus. As I have examined with care the ori- 

 ginal vertebra of the Megalosuurus, figured after Buckland, and referred to 

 by Dr. Mantell at pi. xix. fig. 16 of the same work, I can attach the greatest 

 confidence to the following difierences : — the body of the Megalosaurian 

 vertebra has a pretty deep longitudinal depression below the neurapophysial 

 suture, wanting in the Tilgate vertebra here described. This, however, is 

 not the only distinction ;, below the depression the body of the Megalosaurian 

 vertebra swells out, and is as convex below as it is laterally in the transverse 

 direction, so that the outline of a transverse section would describe five-sixths 

 of a circle: a similar section of No. 123 would be triangular with the apex 

 rounded off'. The Megalosaurian vertebra is more contracted at the middle, 

 and swells out near the articular ends, surrounding those articulations with a 

 thick convex border : in No. 123 the lateral meet the marginal surfaces at a 

 somewhat acute angle ; but the silky striated surface of the Crocodilian ver- 

 tebra, and the smooth and polished surface of the Megalosaurian one, would 

 effectually serve to distinguish even fragments from the middle of the body 

 of each. 



The following are dimensions of the two vertebrae of the large Wealden 

 Crocodilian above described : — 



No. 123. No. 138. 



In. Lines. In, Lines. 



Antero-posterior diameter of the body ... 3 4- 3 10 



Vertical diameter of its articular end .... 2 5 3 2 



Transverse diameter of its articular end ... 2 10 2 9 



Transverse diameter of the middle of the body 2 2 



GONIOPHOLIS CRASSIDENS, O. 



Swanage Crocodile, Mantell. 



Teleosaurus , H. v. Meyer. 



The second form of tooth having the generic characters of those of the 

 Crocodile, which has been discovered in the Wealden and approximate strata, 

 is as remarkable for its thick, rounded and obtuse crown as the teeth of the 

 preceding species are for their slender, compressed, acute and trenchant cha- 

 racter. It consequently approaches more nearly to the teeth which charac- 

 terize the broad and comparatively short-snouted Crocodiles ; but it differs 

 from these in one of the same characters by which the tooth of the Sucho- 

 saurus cultridens differs from those of the Gavials, viz. in the longitudinal 

 ridges which traverse the exterior of the crown. These are, however, more 



