590 



February 25, 1841. 



Sir JOHN WILLIAM LUBBOCK, Bart., V.P., and Treasurer, 



in the Chair. 



The Right Honourable Lord Viscount Melbourne, and the Rev. 

 Mark Aloysius Tierney, were balloted for, and duly elected into the 

 Society. 



The reading of a paper, entitled, " Memoir on a portion of the 

 Lower Jaw of an Iguanodon, and other Saurian Remains discovered 

 in the strata of Tilgate Forest, in Sussex." By Gideon Algernon 

 Mantell, Esq., LL.D., F^R.S., was resumed and concluded. 



When the author communicated to the Royal Society, in the year 

 1825, a notice on the teeth of an unknown herbivorous reptile, 

 found in the limestone of Tilgate Forest, in Sussex, he was in hopes 

 of discovering the jaws, with the teeth attached to it, of the same 

 fossil animal, which might either confirm or modify the inferences 

 he had been led to deduce from an examination of the detached 

 teeth. He was, however, disappointed in the object of his search 

 until lately, when he has been fortunate enough to discover a por- 

 tion of the lower jaw of a young individual, in which the fangs of 

 many teeth, and the germs of several of the supplementary teeth, 

 are preserved. The present paper is occupied with a minute and 

 circumstantial description of these specimens, and an elaborate in- 

 quiry into the osteological characters and relations presented by the 

 extinct animals to which they belonged, as compared with existing 

 species of Saurian reptiles ; the whole being illustrated by numerous 

 drawings. The comparison here instituted furnishes apparently con- 

 clusive proof that the fossil thus discovered is a portion of the lower 

 jaw of a reptile of the Lacertine family, belonging to a genus nearly 

 allied to the Iguana. From the peculiar structure and condition of 

 the teeth it appears evident that the Iguanodon was herbivorous ; 

 and from the form of the bones of the extremities it may be inferred 

 that it was enabled, by its long, slender, prehensile fore-feet, armed 

 with hooked claM^s, and supported by its enormous hinder limbs, to 

 pull down and feed on the foliage and trunks of the arborescent 

 ferns, constituting the flora of that country, of which this colossal 

 reptile appears to have been the principal inhabitant. 



Some particulars are added respecting various other fossil bones 

 found in Tilgate Forest, and in particular those of the HylcBosaurus, 

 or Wealden Lizard (of which genus the author discovered the re- 

 mains of three individuals), and of several other reptiles, as the 

 Megalosauriis, Plesiosaurus, and several species of Steneosaurus^ 

 Pterodactylus, and other Chelonia, as also one or more species of a 

 bird allied to the Heron. All these specimens are now deposited in 

 the British Museum. 



A paper was also read, entitled, " On a Theorem of Fermat." 

 By Sir John William Lubbock, Bart., V.P,, and Treas. R.S. 



