This animal probably lived near estuaries and rivers, and may have derived its food from the Clathrariæ, Zamiæ, Cycades, and other extinct trees, of which the fossil remains abound in the same formations as those yielding the bones and teeth of the Iguanodon.
These formations are the Wealden and the Neocomian or green-sand: the localities in which the remains of the Iguanodon have been principally found, are the Weald of Kent and Sussex: Horsham, in Sussex; Maidstone, in Kent; and the Isle of Wight.
Restorations of the Cycas and Zamia are placed, with the Iguanodon, on the Wealden division of the Secondary Island.
No. 6.—The Hylæosaurus. (Hylæosaurus Owenii.)
The animal, so called by its discoverer, Dr. Mantell, belongs to the same highly organised order of the class of reptiles as the Iguanodon, that, viz., which was characterised by a longer and stronger sacrum and pelvis, and by larger limbs than the reptiles of the present day possess; they were accordingly better fitted for progression on dry land, and probably carried their body higher and more freely above the surface of the ground.
Visiting, in the summer of 1832, a quarry in Tilgate Forest, Dr. Mantell had his attention attracted to some fragments of a large mass of stone, which had recently been broken up, and which exhibited traces of numerous pieces of bone. The portions of the rock, which admitted of being restored together, were cemented, and then the rock was chiselled from the fossil bones, which consisted of part of the back-bone or vertebral column, some ribs, the shoulder bones called scapula and coracoid, and numerous long angular bones or spines which seemed to have supported a lofty serrated or jagged crest, extended along the middle of the back, as in some of the small existing lizards, e.g., the Iguana: cut No. 6. Many small dermal bones were also found, which indicate the Hylæosaurus to have been covered by hard tuberculate scales, like those of some of the Australian lizards, called Cyclodus.
This character of the skin, and the serrated crest, are accurately given in the restoration, the major part of which, however, is necessarily at present conjectural, and carried out according to the general analogies of the saurian form. The size is indicated with more certainty according to the proportions of the known vertebræ and other bones.
No. 6. Diagram of the Slab containing the Bones of Hylæosaurus.