Not long ago the small streams of Northern America and Northern Siberia were peopled with colonies of beavers, and up to the seventeenth century like colonies swarmed in Northern Russia. The flat lands of the four great continents are still covered with countless colonies of mice, ground-squirrels, marmots, and other rodents. In the lower latitudes of Asia and Africa the forests are still the abode of numerous families of elephants, rhinoceroses, and numberless societies of monkeys. In the far north the reindeer aggregate in numberless herds; while still further north we find the herds of the musk-oxen and numberless bands of polar foxes. The coasts of the ocean are enlivened by flocks of seals and morses; its waters, by shoals of sociable cetaceans; and even in the depths of the great plateau of Central Asia we find herds of wild horses, wild donkeys, wild camels, and wild sheep. All these mammals live in societies and nations sometimes numbering hundreds of thousands of individuals, although now, after three centuries of gunpowder civilization, we find but the debris of the immense aggregations of old. How trifling, in comparison with them, are the numbers of the carnivores! And how false, therefore, is the view of those who speak of the animal world as if nothing were to be seen in it but lions and hyenas plunging their bleeding teeth into the flesh of their victims! One might as well imagine that the whole of human life is nothing but a succession of war massacres. Association and mutual aid are the rule with mammals. We find social habits even among the carnivores, and we can only name the cat tribe (lions, tigers, leopards, etc.) as a division the members of which decidedly prefer isolation to society, and are but seldom met with even in small groups. And yet, even among lions "this is a very common practice to hunt in company."(10) The two tribes of the civets (Viverridae) and the weasels (Mustelidae) might also be characterized by their isolated life, but it is a fact that during the last century the common weasel was more sociable than it is now; it was seen then in larger groups in Scotland and in the Unterwalden canton of Switzerland. As to the great tribe of the dogs, it is eminently sociable, and association for hunting purposes may be considered as eminently characteristic of its numerous species. It is well known, in fact, that wolves gather in packs for hunting, and Tschudi left an excellent description of how they draw up in a half-circle, surround a cow which is grazing on a mountain slope, and then, suddenly appearing with a loud barking, make it roll in the abyss.(11) Audubon, in the thirties, also saw the Labrador wolves hunting in packs, and one pack following a man to his cabin, and killing the dogs. During severe winters the packs of wolves grow so numerous as to become a danger for human settlements, as was the case in France some five-and-forty years ago. In the Russian