INTRODUCTION. XV 



bones and teeth should have escaped notice ; especially 

 when the remains of the Cetiosauri and other Reptilian 

 inhabitants of those ancient seas are so abundant. 



From the remote period in which the remains of Mam- 

 mals first make their appearance, to that in which we 

 again get indubitable evidence of their existence, a lapse 

 of time incalculably vast has occurred. We trace it 

 by the successive deposition from seas and estuaries, of 

 enormous masses of rocks of various kinds, the grave- 

 yards of as various extinct forms of animal and vege- 

 table life. The shelly limestone of Stonesfield, which 

 contains the bones of the Amphitheria and Phascolo- 

 theria, lies upon Inferior Oolite. Upon it have been 

 accumulated the strata of the Great Oolite, the Corn- 

 brash and the Forest Marble ; and upon these have been 

 successively piled the Oxford group of Clay,* Calcareous 

 Grit and Coral Rag, the Kimmeridge Clay and Portland 

 Stone. In the extensive range of Wealden Rocks, de- 

 posited after the formation of the Portland Sands by the 

 waters of an immense estuary, and rising to the height 

 of eight hundred feet,-f- no true indications of warm- 

 blooded animals have been hitherto discovered.! Four 

 hundred feet deep of Gautt and (jrreensand rest upon the 

 Wealden, but reveal no trace of Cetacean or other form of 

 Mammalian life. 



* The fossil in the Woodwardian Museum, referred to at p. 520, gives the 

 sole indication of a marine mammal at this period. Although the circumstances 

 of its discovery are far from being satisfactory, I am unwilling to lose sight of 

 this indication, because the cervical vertebrae, whilst they evince by their extreme 

 compression and anchylosis, the cetacean characters, present well-marked specific 

 distinctions from all known recent or fossil species. 



f Lyell, ' Elements of Geology,' 8vo. 1838, p. 345 ; Fitton, 'Geology of 

 Hastings,' p. 58 ; and, especially, Mantell, 'Geology of Sussex,' 4to. 1822. and 

 subsequent Works of this original and successful explorer of the Wealden. 



J See my paper in the 'Proceedings of the Geological Society,' Dec. 17th, 1845, 

 " On the supposed Bones of Wading Birds from the Wealden." 



