As in the case of the platypus, no remains of extinct echidnas are found anywhere except in the superficial deposits of Australia itself. Certain teeth from rocks older than the Chalk, both in Europe and America, may, however, indicate the ancestral stock of the egg-laying group. THE BLACK SWAN (_Cygnus atratus_) When the old Roman poet penned the well-known line, “Rara avis in terris, nigroque simillima cygno,”[A] he little imagined that a black swan was actually living in the then unknown and undreamt-of Antipodes, to be discovered in the dim and distant future by the sailors of a little island in the far north inhabited by fair-haired barbarians of whom he may or may not have heard. [A] “A rare bird in the world, and most like a black swan.” The black swan of Australia, from which the Swan River takes its name, is not perhaps the ideal black swan of the poet, for, as a matter of fact, it has a good deal of white in its wings, although but little of this is visible when the wings are closed, as in the illustration. Moreover, the general colour of the plumage is brownish black, rather than pure black, while the beak is crimson with a white tip, and the eyes are scarlet. From all other swans this species differs by the curling feathers in the region of the shoulder, and the extreme shortness of the tail. Other distinctive features are to be found in the compressed body, the long neck, the small, gracefully carried head, and the absence of a ridge to the beak. The range of the black swan includes both Australia and Tasmania, where it is found not only on the coast, but likewise on the rivers and lakes of the interior. In the earlier days of Australian colonisation it abounded in many parts of the country; but, unfortunately, it is a bird by no means shy, and therefore comparatively easy to shoot, and in consequence of this it has been incessantly and relentlessly persecuted, even the cygnets, while still unable to fly, being hunted among the reeds in the swamps and killed out of pure maliciousness. As a result of this persecution the species has everywhere become scarce, and from some parts of the country has been exterminated. During the winter months these swans collect in small parties and families in South Australia, and return to their breeding-places in spring. The nest is a huge, ill-built structure, made out of coarse materials and lined with sedge. It is generally situated in the neighbourhood of small islands, where the parent birds can readily collect the large amount of material required for its construction. The clutch consists of from five to seven dirty white or pale green spotted eggs, which are brooded with great assiduity by the female, while the male keeps guard in the neighbourhood. The cygnets are clothed in a grey or rufous down, and can swim and dive as soon as they are hatched. The food of both young and adults comprises water-plants of all kinds, as well as worms, molluscs, and small frogs and fishes.