On the subject of the correlation of the French and Belgian discoveries as to primitive man, a most interesting and important communication was made by Dupont to the Geological Society of Belgium in 1892.[21] The veteran explorer of the Belgian caves addresses himself in this paper to a careful comparison of the geological relations, animal remains and human relics in these caves, and in the gravels and 'quaternary' clays associated with them. He arrives at the conclusion, which I had already stated,[22] that these deposits are contemporaneous and show similar stages, but that the mammoth age properly so-called, in which the primitive people fed on the mammoth and its companion the woolly rhinoceros, extended to a later date in Belgium than in France, so that the mammoth age of Dupont and the reindeer age of the French archæologists overlap one another. He notes in connection with this that there is evidence of the continued existence of the mammoth in the so-called reindeer age of France, in the discovery in caves of that period of plates of ivory with the portrait of the mammoth engraved on them. It would therefore appear either that the mammoth earlier became extinct or rare in France, perhaps on account of climatal changes, or perhaps because of destruction by man, or that the habits of the French populations changed in such a way as to cause them to confine themselves to smaller game. In either case, we now find that the whole palanthropic age is one period. On the other hand, Dupont agrees with Mortillet that there is a hiatus, physical, palæontological and anthropological, between the so-called palæolithic and neolithic periods, that is, between the palanthropic and neanthropic ages. [21] _Bulletin de la Société Belge de Géologie_, janvier 1893. This paper should be studied by all interested in the subject. [22] _Fossil Men._ Dupont holds that the plain-dwellers (_Pedionomytes_, as he calls them) were the earliest known men, corresponding to the oldest gravel remains of Dawkins and Prestwich, and points out that their implements are in size and form, though not in material and finish, allied to those of the polished stone age, which might thus be regarded as an improved continuation or revival of this first period. This might be read to mean, as above maintained, that the earliest men were peaceful and perhaps in part agricultural, that they were succeeded by lawless, powerful, artistic and savage peoples, and when the latter were swept away that a remnant of the primitive stock repossessed the land. If this proves to be the net result, it will correspond exactly with our old historical beliefs.