"Many animals and birds which increase very fast in new countries, and which are commonly spoken of as European in their origin, are really as alien to Europe as to their new homes. Thus the rabbit, rat, and mouse are just as truly interlopers in England as in the United States and Australia, having moved thither apparently within historic times, the rabbit from North Africa, the others from southern Asia; and one could no more generalize upon the comparative weakness of the American fauna from these cases of intruders than one could generalize from them upon the comparative weakness of the British, German, and French wild animals. Our wood mouse or deer mouse retreats before the ordinary house mouse in exactly the same way that the European wood mouse does, and not a whit more. Our big wood rat stands in the same relation to the house rat. Casting aside these cases, it seems to me, looking at the mammals, that it would be quite impossible to generalize as to whether those of the Old or the New World are more fecund, are the fiercest, the hardiest, or the strongest. A great many cases could be cited on both sides. Our moose and caribou are, in certain of their varieties, rather larger than the Old World forms of the same species. If there is any difference between the beavers of the two countries, it is in the same direction. So with the great family of the field mice. The largest true arvicola seems to be the yellow-cheeked mouse of Hudson's Bay, and the biggest representative of the family on either continent is the muskrat. In most of its varieties the wolf of North America seems to be inferior in strength and courage to that of northern Europe and Asia; but the direct reverse is true with the grizzly bear, which is merely a somewhat larger and fiercer variety of the common European brown bear. On the whole, the Old World bison, or so-called aurochs, appears to be somewhat more formidable than its American brother; but the difference against the latter is not anything like as great as the difference in favor of the American wapiti, which is nothing but a giant representative of the comparatively puny European stag. So with the red fox. The fox of New York is about the size of that of France, and inferior in size to that of Scotland; the latter in turn is inferior in size to the big fox of the upper Missouri, while the largest of all comes from British America. There is no basis for the belief that the red fox was imported here from Europe; its skin was a common article of trade with the Canadian fur traders from the earliest times. On the other hand, the European lynx is much bigger than the American. The weasels afford cases in point, showing how hard it is to make a general law on the subject. The American badger is very much smaller than the European, and the American otter very much larger than the European otter. Our pine marten, or sable, compared with that of Europe, shows the very qualities of which you speak; that is, its