Australia forms in all regards a distinct zoological province, and its insulated position has tended, in greater measure than is the case with any other part of the world, to confine the distinguishing features of its fauna within its own proper limits. The kangaroo family includes numerous distinct species, from the full-sized kangaroo down to the kangaroo-rat. But not a single one of the tribe is found beyond the limits of Australia and the neighboring island of Tasmania. The opossums, which belong to the same order, are only found elsewhere in the New World. The most remarkable, however, among the members of the Australian animal world is that popularly known as the duck-bill (platypus, or ornithorynchus), which constitutes a puzzle to the naturalist. This is a semi-aquatic creature, about twelve or thirteen inches in length, with the body of an otter, a bill like that of the duck, and which lays eggs. As one of the tribe of Mammalia (to which, by its habits, it belongs), the platypus must be classed under the head of Edentata; while, on the other hand, as being oviparous, it may be regarded as belonging to a totally distinct division of the animal world. The platypus frequents the margins of creeks and pools, but remains mostly in the water, and is only approached with difficulty, on account of its extreme shyness. It has a coating of soft fur, variously shaded from black to silver-gray. Australia is distinguished by an extreme paucity of animal life (in so far as land animals are concerned), in even a higher degree than by the limited number of its native species. This is readily explained by the generally arid character of its interior, the scantiness of the native vegetation, and the consequent difficulty of finding food. The traveler may frequently pass over many hundred miles of country without meeting with a single quadruped, and almost without finding the traces of a single land animal. Its characteristics in the latter regard are undergoing, however, a rapid change: the horse and the ox, introduced by the European settlers, have in some cases reverted to a state of nature, and a herd of wild cattle is now not infrequently met with beyond the ordinary limits of the settlers’ range. The ornithology of Australia is richer and more varied than other branches of its animal life. Its chief distinction consists in the vast proportion of suctorial birds--that is, such birds as derive their principal support from sucking the nectar of flowers. This peculiar organization, restricted in Africa, India, and America to the smallest birds in creation, is here developed very generally, and belongs to species that are as large as an English thrush. The melliphagidæ, or honey-suckers, take the place of the humming-birds of the New World: like all the family to which they belong, they have the tongue terminating in a brush-like bundle of very slender filaments, with which they suck the nectar of flowers.