The dimensions of this aquatic lizard, estimated at twenty-four feet, are calculated to excite surprise. But, as we have already seen, the Ichthyosauri and Teleosauri were of great dimensions, as were also the Iguanodon and Megalosaurus, which were ten times the size of living Iguanas. In all these colossal forms we can only see a difference of dimensions, the aggrandisement of a type; the laws which affected the organisation of all these beings remain unchanged, they were not errors of Nature--_monstrosities_, as we are sometimes tempted to call them--but simply types, uniform in their structure, and adapted by their dimensions to the physical conditions with which God had surrounded them. [Illustration: XXII.--Ideal Landscape of the Cretaceous Period.] In PLATE XXII. is represented an ideal view of the earth during the _Upper Cretaceous_ period. In the sea swims the Mosasaurus; Molluscs, Zoophytes, and other animals peculiar to the period are seen on the shore. The vegetation seems to approach that of our days; it consists of Ferns and Cycadeæ (Pterophyllums), mingled with Palms, Willows, and some dicotyledons of species analogous to those of our present epoch. Algæ, then very abundant, composed the vegetation of the sea-shore. We have said that the terrestrial flora of the Upper Cretaceous period was nearly identical with that of the Lower. The marine flora of these two epochs included some Algæ, Confervæ, and Naïadæ, among which may be noted the following species: _Confervites fasciculatus_, _Chondrites Mantelli_, _Sargassites Hynghianus_. Among the Naïadæ, _Zosterites Orbigniana_, _Z. lineata_, and several others. The _Confervæ_ are fossils which may be referred, but with some doubt, to the filamentous Algæ, which comprehend the great group of the Confervæ. These plants were formed of simple or branching filaments, diversely crossing each other; or subdivided, and presenting traces of transverse partitions. The _Chondrites_ are, perhaps, fossil Algæ, with thick, smooth branching fronds, pinnatifid, or divided into pairs, with smooth cylindrical divisions, and resembling _Chondrus_, _Dumontia_, and _Halymenia_ among living genera. The _Sargassites_, finally, have been vaguely referred to the genus _Sargassum_, so abundant in tropical seas. These Algæ are distinguished by a filiform, branched, or ramose stem, bearing foliaceous appendages, regular, often petiolate, and altogether like leaves, and globular vesicles, supported by a small stalk. * * * * *