Hastings Sand and Weald Clay. 207 



sands form the lower portion, though they are largely 

 interstratified with beds of clay, and sometimes, by 

 changes of character, the sands and clays of the series 

 pass into each other. In the various beds are found 

 Ferns of the genera Alethopteria, Otopteris, and 

 Sphenopteris, the latter sometimes standing erect, as if 

 in the position of growth. Coniferous wood and 

 Cycadeous plants also occur. With rare exceptions, the 

 shells are of fresh-water genera, viz. ten species of Unio, 

 five species of Cyrena, besides Cyclas, Melanopsis, 

 Melania, and Paludina, together with Cypris, C. 

 Valdensis, and the strata containing these are sparingly 

 interstratified with beds containing Ostrea, Corbula, 

 and Mytilus. Several remarkable reptiles occur in the 

 Weald, of the order Dinosauria, belonging to the genera 

 Hylceosaurus, Megalosaurus, Iguanodon, Plesio- 

 saurus, and Pterodactylus, together with nine species 

 of Crocodilia, of seven genera. The Iguanodon was first 

 described by Dr. Mantell as an herbivorous reptile of 

 gigantic size. Its teeth were serrated like those of the 

 modern Iguana, but unlike them it masticated its food. 

 Various fish, of the Placoid and Granoid orders, also occur 

 in the Wealden. The strata composing the Hastings 

 Sand series are about 700 feet thick. 



The overlying beds of Weald Clay are of about 

 equal thickness, and spread in a broad plain, or series 

 of low undulations, all round the more hilly country 

 of the sands. They lie between these sands and the over- 

 lying Atherfield Clay and Lower Grreensand. It is in 

 this clay that thin bands of the well-known Sussex 

 marble occurs, so much used in old times for monu- 

 mental purposes in churches, good examples of which 

 may be seen in Westminster Abbey. It is formed 

 chiefly of the agglomerated shells of Paludina fluvi- 



