OF CREATION. 



209 



one series of operations, and the commencement of 

 another, between the deposit of any of the oolitic 

 beds, commonly so called ; nor does it appear that 

 any great and sudden changes took place, at least till 

 after the termination of the Wealden deposits. The 

 latter present to our notice some additional and 

 remarkable species of animal remains ; but this is not 

 astonishing, since the beds are extensive and of fresh- 

 water instead of marine origin. On the other hand, 

 many species are continued into the Wealden beds 

 from the oolites ; and some pass through that series, 

 their remains appearing again in the newer sandy 

 beds at the commencement of the cretaceous period. 

 The local deposit called " Wealden, 1 ' as it is seen in 

 the south-east of our island, possesses great interest, 

 arising from the presence of a series of fresh-water 

 fossiliferous beds, chiefly of sand with imperfect bands 

 of shelly limestone, terminated by a thick deposit of 

 clay. The main interest arises from the fact that these 

 were probably formed in an estuary, or at the mouth 

 of some great river, and therefore in the immediate 

 vicinity of a tract of land. Fresh-water shells and 

 crustaceans, together with land plants, insects, &c., 

 are here associated with fishes, which may, indeed, 

 have lived in an estuary, but which present no distinct 

 mark of fresh-water origin. Here, once more, we meet 

 with land reptiles associated with aquatic crocodilian 

 genera ; and some of these land reptiles, like those of 

 the older period, exhibit a remarkable resemblance 

 to the pachydermal quadrupeds, extending, indeed, 

 in this case to the possession of distinctly herbivorous 

 habits. These species, again, are not alone they 

 are associated with the very same gigantic carnivor- 



