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For the purpose of zoological comparison, we may class them in four main divisions. 1. The Ladrone and Caroline Islands; 2. New Caledonia and the New Hebrides; 3. The Fiji, Tonga, and Samoa Islands; 4. The Society, and Marquesas Islands. The typical Polynesian fauna is most developed in the third division; and it will be well to describe this first, and then show how the other islands diverge from it, and approximate other sub-regions. Fiji, Tonga, and Samoa Islands-The land-birds inhabiting these islands belong to 41 genera, of which 17 are characteristic of the Australian region, and 9 more peculiarly Polynesian. The characteristic Australian genera are the following: Petroica (Sylviidae); Lalage (Campephagidae); Monarcha, Myiagra, Rhipidura (Muscicapidae); Pachycephala (Pachycephalidae); Rectes (Laniidae); Myzomela, Ptilotis, Anthochaera (Meliphagidae); Amadina, Eythrura, (Ploceidae); Artamus (Artamidae); Lorius (Trichoglossidae); Ptilopus, Phlogaenas (Columbidae); Megapodius (Megapodiidae). The peculiar Polynesian genera are:—Tatare, Lamprolia (Sylviidae); Aplonis, Sturmodes (Sturnidae); Todiramphus (Alcedinidae); Pyrhulopsis, Cyanoramphus, (Platycercidae); Coriphilus (Trichoglossidae); Didunculus (Didunculidae). The wide-spread genera are Turdus, Zosterops, Hirundo, Halcyon, Collocalia, Eudynamis Cuculus, Ianthaenas, Carpophaga, Turtur, Haliaeetus, Astur, Circus, Strix, Asio. The aquatic birds are fifteen in number, all wide-spread species except one—a form of moor-hen (Gallinulidae), which has been constituted a new genus Pareudiastes. Society, and Marquesas Islands-Here, the number of genera of land-birds has considerably diminished, amounting only to 16 in all. The characteristic Australian genera are 5;-Monarcha, Anthochaera, Trichoglossus, Ptilopus, and Phlogoenas. The Polynesian genera are 4;-Tatare, Todiramphus, Cyanoramphus, Coriphilus, and one recently described genus, Serresius, an extraordinary form of large fruit pigeon, here classed under Carpophaga. These remote groups have thus all the character of Oceanic islands, even as regards the rest of Polynesia, since they possess hardly anything, but what they might have received by immigration over a wide extent of ocean. Ladrone, and Caroline Islands—These extensive groups of small islands are very imperfectly known, yet a considerable number of birds have been obtained. They possess two peculiar Polynesian genera, Tatare and Sturmodes; one peculiar sub-genus, Psammathia (here included under Acrocephalus); and ten of the typical Australian genera found in Polynesia, Lalage, Monarcha, Myiagra, Rhipidura, Myzomela, Brythrura, Artamus, Phlogoenas, Ptilopus, and Megapodius, as well as the Papuan genus Rectes, and the Malayan Calornis;–so that they can be certainly placed in the sub-region. Genera which do not occur in the other Polynesian islands are, Acrocephalus, (sg. Psammathia) originally derived perhaps from the Philippines; and Caprimulgus, a peculiar species, allied to one from Japan. New Caledonia, and the New Hebrides.—Although these islands seem best placed with Polynesia, yet they form a transition to Australia proper, and to the Papuan group. They possess 30 genera of land-birds, 18 of which are typical of the Australian region; but while 13 are also Polynesian, there are 5 which do not pass further east. These are Acanthiza, Eopsaltria, Gliciphila, Philemon, and Ianthaenas. The peculiar Polynesian genus, Aplonis, of which three species inhabit New Caledonia, link it to the other portions of the sub-region. The following are the genera at present known from New Caledonia:—Turdus, Acanthiza, Campephaga, Lalage, Myiagra, Rhipidura, Pachycephala, Eopsaltria, Corvus, Physocoraz (s.g. of Corvus, allied to the jackdaws), Glicphila, Anthochaera, Philemon, Zosterops, Erythrura, Aplonis, Artamus, Cuculus, Halcyon, Collocalia, Cyanoramphus, Trichoglossus, Ptilopus, Carpophaga, Macropygia, Ianthaenas, Chalcophaps, Haliastur, Accipiter. The curious Rhinochetus jubatus, forming the type of a distinct family of birds (Rhinochetidae), allied to the herons, is only known from New Caledonia. It thus appears, that not more than about 50 genera and 150 species of land-birds, are known from the vast number of islands that are scattered over the Central Pacific, and it is not probable that the number will be very largely increased. Some of the species, as the Eudynamis taitensis and Tatare longirostris, range over 40° of longitude, from the Fiji Islands to the Marquesas. In other genera, as Cyanoramphus and Ptilopus, each important island or group of islands, has its peculiar species. The connection of all these islands with each other, on the one hand, and their close relation to the Australian region, on the other, are equally apparent; but we have no sufficient materials for speculating with any success, on the long series of changes that have brought about their existing condition, as regards their peculiar forms of animal life. Sandwich Islands—This somewhat extensive group of large islands, is only known to contain 11 genera and 18 species of indigenous land-birds; and even of this small number, two birds' of prey are wide ranging species, which may well have reached the islands during their present isolated condition. These latter are, Stric delicatula, an owl spread over Australia and the Pacific ; and Asio accipitrinus, a species which has reached the Galapagos from S. America, and thence perhaps the Sandwich Islands. Of the remaining 8 genera, one is a crow (Corvus hawaiensis), and another a fishing eagle (Pandion solitarius), of peculiar species; leaving 7 genera, which are all (according to Mr. Sclater) peculiar. First we have Chasiempis, a genus of Muscicapidae, containing two species (which may however belong to distinct genera); and as the entire family is unknown on the American continent these birds must almost certainly be allied to some of the numerous Muscicapine forms of the Australian region. Next we have the purely Australian family Meliphagidae, represented by two genera,_Moho, an isolated form, and Chaetoptila, a genus established by Mr. Sclater for a bird before classed in Entomyza, an Australian group. The four remaining genera are believed by Mr. Sclater to belong to one group, the Drepanididae, altogether confined to the Sandwich Islands. Two of them, Drepanis and Hemignathus, with three species each, are undoubtedly allied; the other two, Locops and Psittirostra, have usually been classed as finches. The former seem to approach the Dicaeidae; and all resemble this group in their coloration.
The aquatic birds and waders all belong to wide-spread genera, and only one or two are peculiar species. The Sandwich Islands thus possess a larger proportion of peculiar genera and species of land-birds than any other group of islands, and they are even more strikingly characterised by what seems to be a peculiar family. The only other class of terrestrial animals at all adequately represented on these islands, are the land shells; and here too we find a peculiar family, subfamily, or genus (Achatinella or Achatinellidae) consisting of a number of genera, or sub-genera-according to the divergentviews of modern conchologists, and nearly 300 species. The Rev. J. T. Gulick, who has made a special study of these shells on the spot, considers that there are 10 genera, some of which are con'fined to single islands. The species are so restricted that their average range is not more than five or six square miles, while some are confined to a tract of only two square miles in extent, and very few range over an entire island. Some species are confined to the mountain ridges, others to the valleys; and each ridge or valley possesses its peculiar species. Considerably more than half the species occur in the island of Oahu, where there is a good deal of forest. Very few shells belonging to other groups occur, and they are all small and obscure; the Achatinellae almost monopolising the entire archipelago. Remarks on the probable past history of the Sandwich Islands. —The existence of these peculiar groups of birds and landshells in so remote a group of volcanic islands, clearly indicates that they are but the relics of a more extensive land; and the reefs and islets that stretch for more than 1,000 miles in a westnorth-west direction, may be the remains of a country once sufficiently extensive to develope these and many other, now extinct, forms of life." Some light may perhaps be thrown on the past history of the Sandwich Islands, by the peculiar plants which are found on their mountains. The peak of Teneriffe produces no Alpine plants of European type, and this has been considered to prove that it has been always isolated; whereas the occurrence of North Temperate forms on the mountains of Java, accords with other evidence of this island having once formed part of the Asiatic contiment. Now on the higher summits of the Sandwich Islands, nearly 30 genera of Arctic and North Temperate flowering plants have been found. Many of these occur also in the South Temperate zone, in Australia or New Zealand; but there are others which seem plainly to point to a former connection with some North Temperate land, probably California, as a number of islets are scattered in the ocean between the two countries. The most interesting genera are the following –Silene, which is wholly North Temperate, except that it occurs in S. Africa; Vicia, also North Temperate, and in South Temperate America; Fragaria, with a similar distribution; Aster, widely spread in America, otherwise North Temperate only ; Vaccinium, wholly confined to the northern hemisphere, in cold and temperate climates. None of these are found in Australia or New Zealand; and their presence in the Sandwich Islands seems clearly to indicate a former approximation to North Temperate America, although the absence of any American forms of vertebrata renders it certain that no actual land connection ever took place. Recent soundings have shown, that the Sandwich Islands rise from a sea which is 3,000 fathoms or 18,000 feet deep; while there is a depth of at least 2,000 fathoms all across to California on one side, and to Japan on the other. Between the Fiji Islands, New Caledonia, the Solomon Islands, and Australia, the depth is about 1,300 fathoms, and between Sydney and New Zealand 2,600 fathoms; showing, in every case, a general accordance between the depth of sea and the approximation of the several faunas. In a few more years, when it is to be hoped we shall know the contour of the sea-bottom better than that of the continents, we shall be able to arrive at more definite and trustworthy conclusions as to the probable changes
* A new genus of Beetles (Apterocyclus) of the family Lucanidae, has recently been described from the Sandwich Islands, and it is said to be most nearly related to a group inhabiting Chili, an indication either of the great antiquity of the fauna, or of the varied accidental migrations from which it has had its origin.