192 REPORT — 1841. 



yards Iiigh, and is continually weai'ing away by the sea washing against it: 

 and, if I may judge by what has happened in my own memory, it must have 

 extended beyond these bones less than a century ago. There are several regu- 

 lar strata or layers of stone, of some yards thickness, that run along the cliff 

 nearly parallel to tlie horizon and to one another. I mention this to obviate an 

 objection, that this animal may have been upon the surface, and in a series of 

 years may have sunk down to where it lay, which will now appear impossible, 

 at least when the stones, &c.. have had their present consistence*." 



It must be obvious, indeed, that the regular succession of horizontal layers, 

 — "beginning from the top, of earth, clay, marble, stones, both hard and soft, of 

 various thicknesses, till it comes down to the black slate or alum rockf," — 

 mounting to the height of near two hundred feet above the petrified skeleton, 

 could not have been the result of the deposit of a temporary overflow of di- 

 luvial waters continuing for a few months, supposing even those Avaters to 

 have been thickly charged with the ruined surface of the old earth. Succes- 

 sion of strata, as of all other phsenomena, must take place in successive periods 

 of time ; the hundredth layer of lias, counting downwards, which contained 

 the skeleton of the strange Crocodile, must once have been the uppermost, and 

 some time must have elapsed between the deposition of that stratum with its 

 organized contents and the deposition of the succeeding layer above. 



If the fossilized bones of the animals described in the pi-esent memoir had 

 been drifted to this island by a flood, they would be found mingled together 

 in the superficial strata usually termed ' diluvial,' and would characterize no 

 particular formation or locality. But the reverse of this is the fact ; and it is 

 the cumulative evidence of the limitation of certain genera to particular for- 

 mations that gives its chief value to the present class of researches. 



In the most superficial fossiliferous deposits which indicate the last opera- 

 tion of a body of v/ater, either frozen or fluid, upon the surface of the British 

 islands, no remains of reptiles have come under my observation. Cuvier alludes 

 to a single bone of a crocodile said to have been found associated with the 

 usual fossils of the drift or diluvium at Brentford J : but no other evidence 

 of any other species or genus of Reptile, which is now confined to warmer 

 regions of the globe, has yet been recognized in the British strata called di- 

 luvial, or in any that are more recent than the oldest Tertiary formations. 



In these Eocene beds, accumulated in some localities to the thickness of 

 three hundred feet and upwards, the remains of crocodiles, tortoises, trio- 

 nyxes, turtles, and large serpents, are more or less common. These fossils 

 severally exhibit well-marked and unequivocal specific differences when com- 

 pared with the bones of their known existing congeners ; but their osteology 

 does not present any modifications of generic value. The nearest approach 

 to this degree of deviation occurs in the Eocene Chelonian Reptiles, as in 

 that species of turtle from Sheppey, which combines the jaws of a Trionyx 

 with the bony helmet of a Turtle, and presents an extent of ossification of the 

 buckler nearly equalling that of an Erays. The Eocene Crocodile exhibits 

 all the characters of the osseous and dental systems M'hich distinguish the 

 genus as restricted in the latest systems of Erpetology ; and whilst it cannot 

 be identified with any known species, most resembles, not the commonest and 

 nearest existing Crocodile, as that of the Nile, but a rarer and more remote 

 one, viz. the Crocodilus Schlcgelii of Borneo. Not any species of Reptile of 

 the Tertiary strata has been discovered in the chalk upon which those strata 

 immediately rest. 



* Philosophical Transactions, 1758, p. 688. t Ibid., p. 789. 



X Dr. Buckland has suggested to me that this bone was probably washed out of the clay 

 beneath the diluvium, 



