84 MR SMITH ON THE CHANGES 



pits or marine beds, those of the rhinoceros,* the Swedish 

 elk f (Cervus alces), and the Irish elk J (C. Megaceros). 

 It may be questioned, however, whether either of the elk spe- 

 cies belong to the tertiary epoch. But, although, in this as 

 in many other cases, it may not be possible to say whether 

 certain deposits belong to the present or the tertiary periods, 

 in theory the line of demarcation is an obvious one, viz. 

 the difference of organic life. 



The creation of man, apart from all other considerations, 

 and regarded merely as a physical event, effected a change 

 in the fauna ; and as it is the latest with which we can be 

 cognisant, it forms the boundary between the two periods. 

 But, in practice, the mere absence of a single species may 

 often lead to erroneous inferences. The earth was probably 

 tenanted by man long before he became an inhabitant of 

 these Islands; and therefore, the absence of his remains, 

 or of works of art, is not of itself a proof that a deposit does 

 not belong to the recent period. 



Mr Lyell informs me, that, in future editions of his work, 

 he means to extend the term " recent, so as to comprehend 

 every deposit in which all the fossil-shells are of recent or 

 living species, whether such strata can be shewn to belong 

 to the historical period or not. This modification of my for- 

 mer arrangement will be found more convenient in practice, 

 because all the subdivisions, the eocene, miocene, pliocene, 

 and recent, will then be founded on purely conchological 

 considerations. If any of the species of shells are extinct, 

 even the smallest proportion, I term the strata newer plio- 



• Notices of the rhinoceros in Scotland, will he found in the Wern . 

 Mem. vol. iv. p. 582, and vol. v. p. 573. Additional notices will be found 

 in the controversy between Drs Fleming and Buckland, respecting the 

 animals extirpated by man, or destroyed by the deluge. Edin. Phil. 

 Journal, vols. xi. and xii. 



t There is a head and horns of the elk from a marl-pit in Perthshire 

 preserved in the Hunterian Museum. 



J Vid. New Stat. Acct, Ayrshire, p. 353. 



