96' PROOFS OF LONG LAPSE OF TIME. 



In the midway regions of the secondary strata, are the 

 earliest remains yet discovered of Cetacea.* In the tertiary 

 formations, we find both Birds, Cetacea, and terrestrial 

 Mammaha, some referable to existing genera, and all to 

 existing orders. See PI. 1, fig. 73 — 101. 



Thus it appears, that the more perfect forms of animals 

 become gradually more abundant, as we advance from the 

 older into the newer series of depositions : whilst the more 

 simple orders, though often changed in genus and species, 

 and sometimes losing whole families which are replaced by 

 new ones, have pervaded the entire range of fossiliferous 

 formations. 



The most prolific source of organic remains has been the 

 accumulation of the shelly coverings of animals which occu- 

 pied the bottom of the sea during a long series of consecu- 

 tive generations. A large proportion of the entire substance 

 of many strata is composed of myriads of these shells re- 

 duced to a comminuted state by the long continued move- 

 ments of water. In other strata, the presence of countless 

 multitudes of unbroken corallines, and of fragile shells, 

 having their most deUcate spines, still attached and undis- 

 turbed, shows that the animals which formed them, Hved 

 and died upon or near the spot where these remains are 

 found. 



Strata thus loaded with the exuviae of innumerable gene- 

 rations of organic beings, afford strong proof of the lapse of 

 long periods of time, wherein the animals from which they 

 have been derived, lived and multiplied and died, at the 

 bottom of seas which once occupied the site of our present 

 continents and islands. Repeated changes in species, both 

 of animals and vegetables, in succeeding members of diffe- 



* There is, in the Oxford Museum, an ulna from the great Oolite of 

 Enstone near Woodstock, Oxen, which was examined by Cuvier, and pro- 

 nounced to be cetaceous ; and also a portion of a very large rib, apparently 

 of a whale, from the same locality. 



