Dr. Mantell also was the first to prove, from the nature of the Wealden strata, that they were deposited in or near the estuary of a mighty river. With regard to the aspect of the country in which the Iguanodon flourished, he showed that coniferous trees probably clothed its Alpine regions; palms and arborescent ferns, and cycadaceous plants (_i.e._ plants resembling the modern zamia, or "false palm"), constituted the groves and forests of its plains and valleys; and in its fens and marshes the equisetaceæ (mare's-tails) and plants of a like nature prevailed. [Illustration: Plate VII. A GIGANTIC DINOSAUR, IGUANODON BERNISSARTENSIS. Length about 30 feet.] The Iguanodons of the Wealden epoch did not live and die where their bones are now found--the condition in which their fossil relics occur proves that they floated down the streams and rivers, with rafts of trees and other spoils of the land, till, arrested in their course, they sank down and became buried in the fluviatile and sometimes marine sediments then being slowly laid down. In this way only can we account for the generally broken and rolled condition of the bones, their separation from each other, the numerous specimens of teeth which must have been detached from their sockets, and the broken stems and branches of trees without leaves that have been found in the Wealden strata of England. Since the days of Dr. Mantell, the remains of Iguanodon, or closely allied genera, have been found on the continent, in other parts of England, and in North America, in strata of various ages, from the Trias or New Red Sandstone to the Chalk (see Table of Strata, Appendix I.). The American Hadrosaurus must have decidedly resembled the Iguanodon. The beautiful restoration by our artist (plate VII.) is based upon the Belgian specimens described in the following chapter. CHAPTER VII. DINOSAURS (_continued_). "Everything in Nature is engaged in writing its own history: the planet and the pebble are attended by their shadows, the rolling rock leaves its furrows on the mountain side, the river its channel in the soil, the animal its bones in the stratum, the fern and the leaf inscribe their modest epitaphs on the coal, the falling drop sculptures its story on the sand and on the stone,--not a footstep on the snow or on the ground, but traces in characters more or less enduring the record of its progress."--Emerson.