marshes, feeding on the succulent vegetation, and often swimming in the water. Footprints prove that when on land it walked habitually on its hind-limbs. [Illustration: Skeleton of _Iguanadon bernissartensis_. (After Dollo.)] The earliest remains of _Iguanodon_ were found by Dr G. A. Mantell in the Wealden formation of Sussex, and a large part of the skeleton, lacking the head, was subsequently discovered in a block of ragstone in the Lower Greensand near Maidstone, Kent. These fossils, which are now in the British Museum, were interpreted by Dr Mantell, who made comparisons with the skeleton of _Iguana_, on the erroneous supposition that the resemblance in the teeth denoted some relationship to this existing lizard. Several of the bones, however, could not be understood until the much later discoveries of Mr S. H. Beckles in the Wealden cliffs near Hastings; and an accurate knowledge of the skeleton was only obtained when many complete specimens were disinterred by the Belgian government from the Wealden beds at Bernissart, near Mons, during the years 1877-1880. These skeletons, which now form the most striking feature of the Brussels Museum, evidently represent a large troop of animals which were suddenly destroyed and buried in a deep ravine or gully. The typical species, _Iguanodon mantelli_, measures 5 to 6 metres in length, while _I. bernissartensis_ (see fig.) attains a length of 8 to 10 metres. They are found both at Bernissart and in the south of England, while other species are also known from Sussex. Nearly complete skeletons of allied reptiles have been discovered in the Jurassic and Cretaceous rocks of North America. REFERENCES.--G. A. Mantell, _Petrifactions and their Teaching_ (London, 1851); L. Dollo, papers in _Bull. Mus. Roy. d'Hist. Nat. Belg._, vols. i.-iii. (1882-1884). (A. S. Wo.) IGUVIUM (mod. Gubbio, q.v.), a town of Umbria, situated among the mountains, about 23 m. N.N.E. of Perusia and connected with it by a by-road, which joined the Via Flaminia near the temple of Jupiter Appenninus, at the modern Scheggia. It appears to have been an important place in pre-Roman times, both from its coins and from the celebrated _tabulae Iguvinae_ (see below).