of which we are in search, yet we know not at what distance it may still be from us; nor, indeed, can we be certain in what direction it lies, nor even whether it will ultimately be discovered. Whether or no, traces of human existence will eventually be found in deposits belonging to Miocene, or even earlier, times, I may take this occasion of remarking that the evidence hitherto adduced on this point by continental geologists is, to my mind, after full and careful examination still very far from satisfactory. At the same time, judging from all analogy, there can be but little doubt that the human race will eventually be proved to date back to an earlier period than the Pleistocene or Quaternary, though it will probably not be in Europe that the evidence on this point will be forthcoming.
The instruments of stone, found in ossiferous caves and in ancient alluvial deposits, associated with remains of a fauna now in great part extinct, belong to a period which has been termed by Sir John Lubbock, the Palæolithic, in contradistinction to the Neolithic Period, the relics of which are usually found upon, or near, the surface of the soil. By others, the more familiar, even if less accurately discriminative, terms of Cave Period and River-drift, or even Drift Period, have been adopted.
Though I propose in these pages to treat of the implements from the caves and from the river-gravels separately, it must not be supposed that there exists of necessity any demonstrable difference in the age of the two classes of relics. On the contrary, though there can be but little doubt that the deposition of the implement-bearing beds, both in the one case and the other, extended over a very considerable space of time, and that therefore neither all of the cave-deposits nor all of the river-drifts can be regarded as absolutely contemporaneous; yet there appears every probability that some, at least, of the deposits in each of the two classes synchronize; and that some caves were being partially filled with earth containing relics of human workmanship and animal remains, at the same time that, in certain ancient river-valleys, alluvial drifts were being formed with similar works of man and bones of animals belonging to the same fauna, incorporated in them.
And yet, as a rule, the character of a group of implements collected from the cave-deposits differs in its general facies from one obtained from the old River-drifts. This is no doubt mainly due to the different conditions under which the two deposits were
