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Show 1882.1 FROM PERU AND CHILI. 529 two well-marked species, was probably, unless the direction of currents has materially altered, by Humboldt's current northwards to the equator, thence across the comparatively feeble and conflicting equatorial currents, until the north equatorial drift led to the shores of Japan. On the coast of California occurs Larus heermanni, another member of this group, with an entirely black tail, and a hood in the immature state; the head gets lighter with age, but the underparts are washed with the dark grey so characteristic of Pacific forms. It has no very close ally in existence ; for Larus modestus, a much slenderer Gull, restricted to the coasts of Peru and Chili, only resembles it in the hood of immaturity and in general coloration, and differs from it in having a tendency to lose the black markings on the rectrices with advance in age. And the isolated Larus fuliginosus, found only in the Galapagos group, differs from the other Pacific Gulls in having a hood at all ages and in losing the markings on the rectrices at maturity. It would seem as if this smoke-coloured species, strauded at the Galapagos, might be the nearest living representative of the ancestor of all these Pacific forms, and the one which at the same time links them to the type of the northern hemisphere. Between South America and the neighbourhood of New Zealand and Australia only Terns are found, no Gull of any kind being on record. Even L. dominicanus is absent from the South-Pacific islands, its line of connexion between South America and New Zealand being by the South Atlantic. But along the southern shores of Australia, from King George's Sound to Tasmania, and (according to the labels on the specimens obtained by the Antarctic expedition) in New Zealand, is found a large dark-mantled Gull, Larus pacificus, Lath., which has an immense blunt bill of peculiar form, somewhat like that of L. scoresbii, and further resembles the Pacific group in that the adult has a broad black band across the rectrices. It is an isolated form ; but although it may be difficult to explain its existence at the junction of the waters of the South Pacific and South Atlantic, the fact seems worthy of attention. Apart from conjectures, there can be no doubt that the connexion between the pelagic birds of the northern and southern hemispheres is much closer in the Pacific than in the Atlantic. The closer resemblance between Stercorarius catarrhactes and S. chilensis than between the latter and its present near neighbour, S. antarcticus, is one proof of this; the intermediate position occupied bv Sterna aleutica of the Aleutian Islands, between the ordinary type of northern Tern and the intertropical group of sooty Terns, is still further evidence; but the strongest of all is perhaps in the case of Xema sabinii and X. furcatum. The former, a circumpolar species not known to breed south of the arctic circle, except on the shores of Behring's Sea, extends its breeding-range in the North Pacific as far south as Alaska; and not only the young birds, which are always great wanderers, but also the adults of this species come down in winter as far as 12° S. lat., thus considerably overlapping the ran°-e |