they move slowly from tree to tree, having no need to hurry after food, since they live suspended in the midst of a perennial banquet.

Nearly allied to the sloths were certain huge beasts, now extinct, which formerly inhabited the same Continent—such as the Megatherium and Mylodon, which rivalled or exceeded our largest rhinoceroses in bulk. They fed on the same food which nourishes the sloth, but obviously the branches of no tree could sustain such monsters. They obtained their leafy pasture, therefore, by a different method. Rearing themselves on their massive hind legs and powerful tail, as on a tripod, they embraced the trees with their vigorous arms, and swayed them to and fro, till the tree embraced was prostrated, and literally fell a prey to their efforts. These bulky creatures were protected against that danger which such a mode of life rendered imminent by a specially strong skull structure, which enabled them to bear a broken head with but little inconvenience.

In the same region of the earth are found the ant-eaters and armadillos, and more or less allied to them are the pangolins (Manis) of Africa and Asia. The horny scales which cover the bodies of the last-named animals caused them for some time to be associated with reptiles rather than with beasts, though they are true and perfect mammals. Lastly must be mentioned the aard-vark (Orycteropus) of South Africa.

All these creatures, from the sloths to the aard-vark, are commonly associated together in an order which is termed Edentata.

The whole of the orders of mammals yet mentioned agree in certain important details with respect to their reproductive processes, as well as in certain smaller anatomical peculiarities, and the whole of the creatures included within these orders are (and will be) often spoken of as Placental Mammals.

The only beasts which it yet remains to speak of are grouped in two other orders.

The first of these is called the order Marsupialia, and comprises all opossums (Didelphys), kangaroos (Macropus), phalangers (Phalangista), the Tasmanian wolf (Thylacinus), the dasyures (Dasyurus), the bandicoots (Perameles), and their allies. With the exception of the true opossums (Didelphys), all the members of the order are found in Australia or its vicinity, and nowhere else in the present day; although, as we shall better see hereafter, Europe once possessed animals closely allied to Australian forms of to-day—notably to a pretty little quadruped which bears the generic name Myrmecobius.

As last of the class of beasts, we have two extremely exceptional mammals (both found only in the Australian region), the duck-billed platypus (Ornithorhynchus), and the Echidna. The first of these, as its name implies, has a muzzle quite like the bill of a duck, with a squat, hairy body, and short limbs. The echidna is covered with strong, dense spines, and has a long and slender snout. These creatures together form the order Monotremata—an order which differs very much more from any other Mammalian order than any of the other orders of mammals differ one from another.

Thus, that great group which embraces man and beasts, and which group ranks as a "class"—the class Mammalia—comprises (as we have now seen) a number of subordinate groups termed "orders," the orders being made up of families, and these again of genera.

It would be impossible as yet (when hardly any anatomical facts have been even referred to) to give the characters of the class Mammalia. It must at present suffice to point out that, in addition to mammary glands, the creatures have hot blood, and the body bears more or less hair—at least at some time of life.

We may now pass to the next class, that of birds—the class Aves. In spite of the great multitude of kinds which ornithologists enumerate—upwards of ten thousand species—there is very much less diversity of form amongst birds than there is amongst beasts.

Starting in the present class as in the preceding one from the most familiar kinds, we may begin with the domestic fowl. This is one of an "order" to which belong the peacock, all pheasants and tragopans (three forms which have their home in Central and Southern Asia), also the Guinea fowls (African forms), and the turkeys and curassows, which are American representatives of the order. Besides these may be mentioned partridges, grouse, black-cock, the capercalzie and quails, and, lastly, the megapodius or bush-turkey of Australia. This last is the only bird which hatches its eggs by artificial heat, depositing them in a mound of earth and decaying vegetable matter, wherein they are hatched fully-fledged, so that they can fly away immediately on leaving the egg. All the birds yet mentioned are called gallinaceous birds, or Gallinæ, and sometimes Rasores or "Scratchers."

More or less allied to them are the doves and pigeons, which form the order Columbæ, in which the curious ground-pigeon Didunculus is included—a form which presents an interesting resemblance to the celebrated and extinct dodo of Mauritius, long known only by certain pictures, and a foot and head preserved, one in the British Museum, and the other in the Ashmolean Museum of Oxford.

Our sparrows, robins, and all our song birds are members of an exceedingly numerous "order" "Paseres." In it are included the crows (with those gaily-decorated crows, the Birds of Paradise, found only in New Guinea and the Moluccas), the bower birds and the lyre bird of Australia; the flycatchers, the pittas (or ground thrushes), the water-ouzel, the weaver birds, the wrens, the tits, the creepers, the honey-eaters, those African gems, the sun birds, and also the swallows.

To another order—the order Macrochires—belong those most beautiful of all birds, the humming birds, found only in America, and long thought to be allied with the really very different sun birds just mentioned. With these may be associated the swifts (which have such marvellous powers of flight) and the wide-gaped goat-suckers or nightjars.

Woodpeckers are considered to form an order (Pici) by themselves, while the cuckoos are thought to be near relations of the beautiful and eccentric toncans, the plaintain-eaters, the touracous, the kingfishers, the hoopoes, the bee-eaters, the hornbills, and the trogons, all, from the cuckoos to the trogons, being included in the order Coccyges.

The parrots form an isolated group of birds—the order Psittaci. Their most peculiar forms are the macaws on the one hand, and the brush-tailed loris on the other. The order Accipitres includes all the birds of prey—that is to say, the eagles, falcons, hawks, buzzards, vultures, and owls. In this order is included the long-legged secretary bird, which looks like a cross between a hawk and heron.

Pelicans, gannets, cormorants (or shags), and darters go together to constitute the order called Steganopodes. The flamingoes are isolated, and by themselves form the order Odontoglossæ. The same is the case with the penguins, which have the order Impennes assigned exclusively to them.

The ducks and geese form alone the order Lamellirostres, in which is included the curious bird Palamedea, which is a goose adapted to live in trees in harmony with its South American forest habitat.

The rails and coots go with the bustards and cranes to constitute the order Alectorides. Similarly the auks, divers, puffins, terns, and grebes, noddies, and guillemots may be associated together in one order—the order Pygopodes. The gulls and petrels form another association—the order Gaviæ; while the plovers, snipes, curlews, peewits, turnstones, &c., constitute the order Limicolæ. The