§ 2. ZOOLOGY OF THE WEALDEN. 485 



saurus (p. 311), Polyptychodon (p. 354), Ichthyosaurus,* 

 Plesiosaurus, and others, of which imperfect vestiges 

 only have been obtained. 



Of the terrestrial fauna and flora, the evidence to be 

 derived from deep sea deposits must of course be scanty. 

 We have however proof that the then dry land was clothed 

 with forests of pines, and that ferns, and plants of the 

 cycadeous tribes, formed the prevailing vegetation ; and that 

 the country was inhabited by Iguanodons, Pterodactyles, 

 and other reptiles. 



2. Zoology of the Wealden. — From data of a like 

 nature, we learn that during the deposition of the Wealden, 

 there was an extensive region traversed by streams and 

 rivers swarming with fishes, crustaceans, and mollusca, 

 of extinct species, but belonging to the same principal 

 types as those which inhabit the fresh waters of tropical 

 climates, under similar conditions : and that then, as now, 

 fluviatile turtles and crocodilian reptiles tenanted the 

 swamps and marshes. 



Of the inhabitants of the land, we have more ample 

 information from the relics engulfed in the deltas and 

 lacustrine sediments, than could be afforded by deposits 

 accumulated in the depths of the ocean, and far from the 

 regions whence they were derived. 



Colossal herbivorous and carnivorous lizards, differing 

 essentially in their organization from all existing reptiles, 

 and of which no vestiges have been discovered in any 

 strata newer than the Chalk, were the principal terrestrial 

 vertebrata of the Wealden epoch. These, together with a 

 few flying reptiles, and lizards of small size, and probably 

 some kinds of wading birds, constituted the entire fauna 

 of the regions which furnished the materials of this for- 



* A new species of Ichthyosaurus, having the fangs of the lower 

 teeth curved, (/. caminjlodon), has lately been found in the Lower- 

 Chalk of Cambridgeshire : see London Geological Journal, No. I. p. 7. 

 K K 2 



