The teeth (Fig. 141), which are the most important and characteristic organs of the whole animal, are imbedded laterally in grooves, or sockets, in the dentary bone; there are three or four sockets of successional teeth on the inner side of the base of the old teeth. The place thus occupied by the edges of the teeth, their trenchant and saw-like form, their mode of curvature, the points where they become broader or narrower which turn them into a species of nippers or scissors--are all suitable for cutting and tearing the tough vegetable substances which are also found among the remains buried with this colossal reptile, a restoration of which is represented in PLATE XXI., p. 296. * * * * * The Cretaceous seas contained great numbers of Fishes, among which some were remarkable for their strange forms. The _Beryx Lewesiensis_ (1), and the _Osmeroides Mantelli_ (2) (Fig. 142), are restorations of these two species as they are supposed to have been in life. The _Odontaspis_ is a new genus of Fishes which may be mentioned. _Ammonites rostratus_ (Fig. 140), and _Exogyra conica_ (Fig. 147), are common shells in the Upper Greensand. [Illustration: XXI.--Ideal scene in the Lower Cretaceous Period, with Iguanodon and Megalosaurus.] The seas of the Lower Cretaceous period were remarkable in a zoological point of view for the great number of species and the multiplicity of generic forms of molluscous Cephalopods. The Ammonites assume quite gigantic dimensions; and we find among them new species distinguished by their furrowed transverse spaces, as in the _Hamites_ (Fig. 132). Some of the _Ancyloceras_ attained the magnitude of six feet, and other genera, as the _Scaphites_, the _Toxoceras_, the _Crioceras_ (Fig. 125), and other Mollusca, unknown till this period, appeared now. Many Echinoderms, or sea-urchins, and Zoophytes, have enriched these rocks with their animal remains, and would give its seas a condition quite peculiar. On the opposite page an ideal landscape of the period is represented (PLATE XXI.), in which the Iguanodon and Megalosaurus struggle for the mastery in the centre of a forest, which enables us also to convey some idea of the vegetation of the period. Here we note a vegetation at once exotic and temperate--a flora like that of the tropics, and also resembling our own. On the left we observe a group of trees, which resemble the dicotyledonous plants of our forests. The elegant _Credneria_ is there, whose botanical place is still doubtful, for its fruit has not been found, although it is believed to have belonged to plants with two seed-leaves, or dicotyledonous, and the arborescent Amentaceæ. An entire group of trees, composed of Ferns and Zamites, are in the background; in the extreme distance are some Palms. We also recognise in the picture the alder, the wych-elm, the maple, and the walnut-tree, or at least species analogous to these. * * * * *