but successively, he has attempted to give the true sequence of the invasion, and assigns all the French caves and river-deposits to "l'âge du grand ours des cavernes, l'âge de l'éléphant et du rhinocéros, l'âge du renne, et l'âge de l'aurochs." It seems to me that there are several fatal objections to this very generally received classification. It is necessary, in the first place, to show which of these animals came here first, before we can say that the age of the Cave-bear preceded that of the Mammoth, or the age of the Mammoth that of the Reindeer, or lastly the age of the Reindeer that of the Aurochs. We must know for certain that this was the true order of their advent; and of this M. Lartet has not advanced any satisfactory proof. It is certainly true that the Mammoth was in. occupation of the Thames valley and of the area which is now covered by the German Ocean before the Reindeer had arrived. That this must necessarily have been the case follows from the fact that the former is a less arctic animal than the latter—being found in the forest-bed of Norfolk, which is proved by its vegetation to have been accumulated under temperate conditions, as well as in company with the Mastodon in the lower basin of the Mississippi. As the evidence stands at present, the Mammoth occupied the same area as the Cave-bear in the Early Pleistocene times, and is as clearly entitled to the first place in classification as the latter animal. If we consider the conditions under which the Pleistocene mammalia invaded Pliocene Europe, we can see at once why the Mammoth preceded the Reindeer. The temperate climate gradually became colder in France, Germany and Britain; and as the cold became more intense in the northern portions, the animals fitted for a cold climate passed southwards and westwards. In this great migration the animals adapted for a temperate or moderately severe climate would be the first to arrive. Were the climate of the extreme north to become so intense as to prevent the sojourn of the Reindeer and Musk-sheep on the shores of the Arctic Ocean, and to affect the whole of the Continent, there would be a steady drift of mammal life from north to south; the Elk and the Wapiti would invade the country of the Bisons, and leave their own district to be occupied by the Reindeer and the Musk-sheep. Indeed, speaking roughly, the zones of animal life which are centred round the north would not alter their relative position, but would be pushed further south, as it were, en masse. If the severity increased, the Reindeer would eventually reach the country of the Bisons, but only to find it in possession of the rearguard of Elks. From this analogy it follows that the animals which are now living in the temperate regions and which lived in Pleistocene Europe, arrived before their more arctic fellow immigrants. And if this be admitted, the Mammoth, the Irish Elk, and the Aurochs are at least as fairly entitled to occupy the first place in classification as the Cave-bear. In Britain the first of these animals has been obtained from the Forest-bed, as well as the Cave-bear, and is therefore of precisely the same relative antiquity. The foreign strata offer no evidence on this point.
A second objection to this theory is to be found in the fact that it
