150 Geological Society. 



can belittle doubt that it extends considerably further. It rests al- 

 most immediately on the clays, containing the well-known suite of 

 pyritous fossils with which the Isle so much abounds, and its level 

 above the beach is stated to be about 1 40 feet. The specimens be- 

 long to the well-known English shells, — Ostrea edulis, Cardium 

 cdule, Buccinum undatum, Fusus antiquus, and Turbo littoreus. 



Dec. 5. — A paper was read, entitled "Observations on the Re- 

 mains of the Iguanodon, and other fossil Reptiles, of the Strata of 

 Tilgate Forest in Sussex," by Gideon Mantell, Esq., F.G.S. R.S. 

 and L.S. 



The author, having noticed the various memoirs and works which 

 have appeared on the organic remains of the fossil reptiles of Sus- 

 sex, proceeded to give a summary account of all that was known 

 upon the subject, and to add descriptions of the various interesting 

 fossils which subsequent discoveries had brought to light. He ob- 

 served that the strata of Sussex, with the exception of diluvial and 

 tertiary deposits, were referrible to two series of formations only, — 

 one, marine, including the chalk and green-sands ; the other, fresh- 

 water, the Wealden : the former, containing fishes, zoophytes, and 

 marine shells ; the latter, herbivorous saurians, turtles, terrestrial 

 plants, and fresh-water shells. He then described the teeth and 

 other bones of the Crocodile, Megalosaurus, Plesiosaurus, Igua- 

 nodon, and Phytosaurus cylindricodon. The head, jaws, and teeth 

 of the last animal were stated to have been found in the Keuper 

 of Germany, and the teeth in the Tilgate beds of Sussex. On 

 the Iguanodon the author offered many new anatomical details: 

 he particularly noticed, — an ungual bone, a clavicle of a most ex- 

 traordinary form, and the thigh- and both leg-bones of the same 

 limb, which exhibited enormous dimensions. He then gave a state- 

 ment of the results of a careful comparison of six different portions 

 of the skeleton of the recent Iguana and the Iguanodon, and stated 

 that from this investigation it appeared the length of the animal 

 was 70 feet, the tail forming about two thirds of the whole. A 

 new fossil reptile was then described, of which a considerable por- 

 tion of the skeleton of the trunk had been lately discovered. The 

 block of stone in which the bones were imbedded was 4| feet by 

 2± feet. It exhibited a chain of 5 cervical and 5 dorsal vertebra?, 

 with corresponding ribs ; and four other vertebrae detached from 

 the column and lying on other parts of the stone. The coracoids 

 and omoplates of both sides were visible, and exhibited a structure 

 so peculiar as to warrant the separation of this new reptile from all 

 recent and fossil genera. With the coracoids of a Lizard, it had 

 the omoplates of a Crocodile. A still more extraordinary pecu- 

 liarity of osteological structure was exhibited in a series of spinous 

 bony apophyses, which, varying in size from 3 to 17 inches in 

 length, and from l~ to 7 in width at the base, maintained a certain 

 parallelism with the vertebral column, as if they had been placed in 

 a line along the back. This circumstance, together with other 

 reasons, induced the author to suggest that they might be the re- 

 mains of a dermal fringe, with which, as in some recent species of 



