74 Professor Owen on British Fossil Beptiles. 



The Bhynchosaurus of the new red-sandstone near Shrews- 

 bury manifests ornithic and chelonian modifications, grafted 

 upon an essentially lacertian type of cranial structure ; no 

 approach even to the form of its extraordinary head being 

 made by any other of the extinct members of the saurian 

 order. The vertebne of the Bhynchosaurus differ from those 

 of existing Hzards, chelonians, and birds, and combine the bi- 

 concave structure with the oblique processes and costal arti- 

 culations of the vertebrae of recent lizards. 



The Labyrinthodonts of the same formation exhibit a dif- 

 ferent but an equally remarkable combination of characters, 

 crocodilian modifications being superinduced upon a funda- 

 mental organization of the Batrachian type. The structure 

 of the teeth in this remarkable family, which is the most com- 

 plex that has hitherto been met with in the whole animal 

 kingdom, is unique in the class of reptiles, and is but partial- 

 ly and comparatively feebly repeated in that of fishes. It is 

 highly probable that the modifications of the locomotive extre- 

 mities were as peculiar as the dental character, if we may 

 judge from the foot-prints of the so-called Cheirotheriiim, to 

 which the Labyrinthodonts alone have at present an equitable 

 claim. 



Finally, the Palaeosaurus, and other genera of the magne- 

 sian conglomerate, like the so-called monitors of Thuringia, 

 are lizards, which combined a thecodont type of dentition with 

 biconcave vertebrae, having the superadded peculiarity of a 

 series of ventricose excavations in the bodies of the vertebrae 

 for the spinal chord, instead of a cylindrical canal. 



Below the new red sandstone system, notwithstanding that 

 the older deposits, as the coal measures, have been more 

 thoroughly explored by man than any other geological forma- 

 tion, no trace of a vertebrate animal more highly organized 

 than a fish has been detected. 



From this survey it is evident, that many races of extinct 

 reptiles have succeeded each other as inhabitants of the por- 

 tion of the earth now forming Great Britain ; their abundant 

 remains, through strata of immense thickness, shew that they 

 existed in great numbers, and probably for many successive 

 generations. Their coprolites prove, that they fed upon or^ 



