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328 places and are associated with the remains of other characteristic arctic animals which breed in the same regions. Thus well-preserved skeletons of arctic fox, having their milk teeth, have been found lying side by side with the bones of the lemmings. As the arctic fox breeds in June, it is obvious that those young individuals must have died in summer.

Our knowledge of the former distribution of the arctic lemmings is no doubt not so full as it will yet be, but already we have ascertained that these creatures ranged as far south as central France and the base of the Alps, in Switzerland, and as far west as Somerset, in England. Besides the arctic fox, many other northern forms were congeners of the lemmings in middle and western Europe, such as mountain hare, muskox, reindeer, glutton, voles of various kinds, ermine, weasel, wolf, common fox, and the now extinct mammoth and woolly rhinoceros. A number of northern birds have also been recorded from the same deposits as those which have yielded relics of the tundra animals. I need mention only ptarmigans, buntings, snow owls, ducks, geese, and swans, all of which are in harmony with the arctic character of the mammals, since the same forms are in our day constant summer visitants in the circumpolar treeless lands.

We may note, further, that just as there is this evidence to the former occupation of middle and western Europe by an arctic fauna, so we have abundant traces in the same regions of a well-marked arctic flora. High northern species of mosses, the polar willow, the dwarf birch, and various other northern plants have been met with in superficial deposits over a very wide area, extending from southern Sweden and England across middle Europe to the foot of the Alps.

We can not doubt, therefore, that true tundra conditions have formerly prevailed at relatively low latitudes in Europe. The widespread distribution of the arctic animals and plants just mentioned points clearly to that and to no other conclusion. We may therefore reasonably infer that the climate of middle Europe must then have approximated in character to that of northern Siberia, the seasons being doubtless strongly contrasted, and thus compelling annual migrations. With the advent of summer the home of the arctic lemmings was invaded by troops of visitants—by mammoth, woolly rhinoceros, wild horse, saiga, and many others, and by numerous birds. An arctic-alpine vegetation clothed the low grounds, which in the warm season doubtless showed wide stretches of bog and marsh and many shallow lakes. Here and there flourished patches and wider tracts of birch and willow scrub, but the land was practically treeless. Man, we know, was an occupant of middle Europe at this time. Perhaps, like the mammoth and the woolly rhinoceros, he may have been rather a summer visitor than a constant denizen, departing for more clement regions at the approach of winter. We shall probably not err in supposing that the winter would have much resemblance to that now experienced in northern