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.
[Illustration: No. 6. Diagram of the Slab containing the Bones of
Hylæosaurus.]