The Grizzly bear is a very different animal; its home is in North America, and it will hunt down a man with such determination that it is very much dreaded by the fur-hunters. The white or Polar bear belongs entirely to the Arctic regions, so that I have often wondered that the great creature which looks so innocent as it dives for the bread which is thrown to it by visitors at the Gardens, or plays with its ball in the water, does not die during our hot summer months. I have heard that the reason why the soles of its feet are so hairy is because in its northern home it is constantly travelling over icefields, sometimes climbing the lofty bergs--and the long hair prevents it from slipping. If so, this is but one more instance showing how perfectly the animals are fitted for the life which they live in their natural state. And now we must pass from this group to another great Division of the Mammalia--the Herbivorous animals, which live, not on the flesh of birds or beasts, which they hunt for themselves, but upon grass and green things. In the first class the Gnawing creatures are placed; you can always know them by their teeth. Perhaps you remember how different the front teeth of a rabbit are from those long, sharp ones which pussy shows now and then when she yawns. By constantly gnawing their food, the teeth of squirrels, hares, rats, mice, dormice, and all animals called Rodents, or Gnawers, would soon be worn away, but that, unlike our teeth, they never cease growing while the creature lives. The most interesting of these creatures is the Beaver, with its webbed hind feet and broad tail. I hope you will some day read about the mud-built houses, and the clever dams which beavers make across the rivers. Mr. Wood says that when they have been tamed they will still go on building dams across one corner of the room in which they are, and collecting boots, brushes, books, all sorts of things, and putting them together industriously; for they still have in captivity the same instinct which teaches them to dam the stream where they build, so that the entrance to their houses may always be below the surface, and never be barred by the ice, during frost. The teeth of horses are differently formed from those of the gnawing animals: at the back they are massive, and act like grindstones, crushing the grain which they eat. The Horse-family includes the patient Ass, and the beautifully marked Zebra of South Africa. I need not tell you that all these animals have only one toe, with that hard and strong toe-nail which is called the hoof. The Ruminants, or animals that chew the cud, are cows, sheep, and goats, deer, giraffes, and camels.