We must not forget the Toothless animals, of which the Ant-eater is the best known. They live upon insects, chiefly white ants, which they catch by tearing open their houses with their strong claws, and then rolling their long tongues among them. The tongue of the ant-eater is covered with a kind of gum, to which the ants stick, and when there is room for not one more, the living mouthful is swallowed. Perhaps your cousins in Australia sometimes tell you about the great Kangaroo, or "Old man," as they call him in that part of the world. By means of his very long and powerful hind legs, and strong tail, he can leap great distances, so rapidly as to outstrip a greyhound. There are many species of kangaroos, but they are all much alike, and belong to the order of Pouched animals; so called because instead of rearing her young in a nest which she has made for them, the mother carries them in a bag. The little creatures at their birth are more helpless than most young animals, and this pouch is their home for some time, and their refuge in danger, even after they have grown beyond the need of her constant care. Australia has no animals like those of other parts of the world, except the dog and the bat; but only one of these pouched animals--the Opossum of America--is not found there. This creature is very like a monkey, and the one best known in the southern states of America is about the size of a cat, and very mischievous--as it sleeps during the day and prowls about at night, in search of birds, eggs, and fruit. It has the power, which some animals possess, of pretending to be dead, when in danger of being caught; and thus it often escapes. Seals and Whales must also be classed among the Mammalia, although they are especially formed to live in the water. Whales, though so much like fishes that they used to be classed with them, have warm blood and do not breathe through gills; so they have to come to the surface of the water every now and then, in order to get air. By-and-by, when you read more, you will understand how it is that the whale, though it breathes as you do, is able to stay under water as long as half an hour at a time. Now, at the end of this long chapter about the Mammalia, let us see what we have been noticing about them. They are put first in the Vertebrate Group, though we have spoken of the birds and fishes before them, because they were made on the Fifth Day. They are generally--for we must not forget the whale--covered with hair or fur, and they feed their young with milk. First of the classes into which the Mammalia are divided, we place the Four-handed creatures--apes and monkeys. Second, the Hand-winged; the bats. Third, the Flesh-eaters; many of them beasts of prey of the Cat-kind and of the Dog-kind. Fourth, the Herbivora; animals which feed upon grasses. Fifth, the Horse-tribe. Sixth, the Ruminants; animals which chew the cud. Seventh, Elephants.