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 'Recent.'
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 proportion 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 Relations of the existing Fauna and Flora of the British Isles;'[1] 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 comprehend 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 chronological relation of the Recent and Post-pliocene to the antecedent periods.
