WEALDEN FORMATIONS. 3 



This side-blow to Dr. Buckland's determination has been repeated by later foreign 

 palaeontologists. M. Deslongchamps, for example, has remarked, " Qu'il n'y a de bien 

 decidement constate, comme Megalosaurus, que les dents ; car les autres pieces 

 osseuses, que Ton rattache a ce genre, y concordent a la verite par la taille et parce 

 qu'elles ont ete trouvee dans les memes bancs, mais non dans le meme bloc."* The 

 Megalosaurus, in fact, was not the only gigantic reptile which the Stonesfield slate was 

 then known to have contained ; but, up to the present time, it has been the sole 

 representative of the Dinosaurian order in that formation ; and the combination of the 

 characteristic modifications of the sacrum, scapular arch, and great limb-bones, 

 in skeletons of the same individual of the Iguanodon, and equally proved to coexist in 

 the Hylaeosaurus, has added greatly to the probability of the disjoined complex sacrum, 

 dorsal, and lumbar vertebrae, coracoid, and the large hollow femur, from the Stonesfield 

 slate, which, though Dinosaurian, were neither Iguanodontal nor Hylaeosaurian, having 

 belonged to a distinct species of great Dinosaur : to no other reptile, indeed, could the 

 portion of jaw, with teeth manifesting in their structure and mode of implantation the 

 same transitional or annectant characters between the Crocodilia and Lacertilia as the 

 above-cited parts of the skeleton present, be, with greater probability, referred, than to 

 the peculiar Dinosaurian Carnivore to which the parts of the skeleton above defined 

 certainly belonged. 



To my own mind the above reasoning, strengthened by repeated instances of the 

 occurrence of Megalosaurian teeth, with vertebrae, sacrum or portions of sacrum, 

 coracoids, and femora, of the same species as those from Stonesfield ascribed to 

 Megalosaurus, in Weal den and Oolitic formations of other localities, has produced a 

 conviction that the parts to be described in the present Monograph do belong to one 

 and the same species. 



There is, moreover, a peculiar smoothness of surface and compactness of exterior 

 osseous layers, common to the portions of toothed jaws with the other parts of 

 the skeleton, that immediately suggest to the practised anatomical eye the idea of their 

 being specifically identical. The microscopic character of the osseous tissue from the 

 above-named bones is also the same ; but on this evidence I should not lay much 

 stress, since the difference is not, at least to me, appreciable between the Megalosaurus, 

 Poikilopleuron, and Streptospondylus, in regard to the microscopic characters of the bone. 



The bodies of the sacral vertebrae, as the five vertebrae of the Megalosaurus first 

 discovered have proved to be,f are remarkable for their median constriction, and the 

 almost cylindrical form of the transverse section of that part; and the repetition of 

 these and some minor characters in vertebrae of the same size from other parts of the 

 trunk, as, e.g., in a detached dorsal and caudal vertebra obtained from Stonesfield 



* ' Sur le Poikilopleuron Bucklandi,' 4to, p. 52. 



+• Report on British Fossil Reptiles, Part II, ' Trans, of the British Association,' 1841, p. 105. 



