6 DEFINITION OF TERMS. CHAP. I. 



fossil quadrupeds belongs to extinct species. I am aware that 

 it may be objected, with some justice, to this nomenclature, 

 that the term Post-pliocene ought in strictness to include all 

 geological monuments posterior in date to the Pliocene; 

 but when I have occasion to speak of these in the aggregate, 

 I shall call them Post-tertiary, and reserve the term Post- 

 pliocene exclusively for Lower Post-pliocene, the Upper Post- 

 pliocene formations being called 6 Eecent.' 



Cases will occur where it may be scarcely possible to draw 

 the line of demarcation between the Newer Pliocene and Post- 

 pliocene, or between the latter and the recent deposits ; and 

 we must expect these difficulties to increase rather than 

 diminish with every advance in our knowledge, and in propor 

 tion as gaps are filled up in the series of geological records. 



In 1839 I proposed the term Pleistocene as an abbreviation 

 for Newer Pliocene, and it soon became popular, because 

 adopted by the late Edward Forbes in his admirable essay 

 on 'The Geological Kelations of the existing Fauna and 

 Flora of the British Isles;'* but he applied the term almost 

 precisely in the sense in which I shall use Post-pliocene in this 

 volume, and not as short for Newer Pliocene. In order to 

 prevent confusion, I think it best entirely to abstain from 

 the use of Pleistocene in future ; I have found that the 

 introduction of such a fourth name (unless restricted solely to 

 the older Post-tertiary formations) must render the use of 

 Pliocene, in its original extended sense, impossible, and it is 

 often almost indispensable to have a single term to compre 

 hend both divisions of the Pliocene period. 



The annexed tabular view of the whole series of fossiliferous 

 strata will enable the reader to see at a glance the chrono 

 logical relation of the Eecent and Post-pliocene to the ante 

 cedent periods. 



* Geological Kelations of the Survey of Great Britain, vol. i. p. 336. 

 existing Fauna and Flora of the London, 1846.) 

 British Isles. (Memoirs of Geological 



