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Show 1878.] MR. D. G. ELLIOT ON THE GENUS PTILOPUS. 515 of its habitat, which also had become islands. In considering the peculiarities of the geographical distribution of these birds, the great physical changes that have taken place in that portion of the globe over which they are dispersed must always be borne in mind. The members of the genus Ptilopus are found in only two of the zoogeographical regions of the earth, viz. the Oriental and Australian. Of these the latter contains by far the great majority of the species ; and, to judge from the material at present available, the Papuan group of the Austro-Malayan Subregion is apparently the head quarters of the genus, The Polynesian Subregion also possesses many species; but they are altogether of a different style of plumage, and constitute almost a division by themselves. I commence the review of this portion of m y subject with the most easterly group of the Pacific islands (in the Polynesian Sub-region of the Australian Region) in which any members of this genus are found, viz. the Marquesas. But two species are met with among these islands-the Pt. dupetit-thouarsii, on Christine Island, and the Pt. mercieri, from Nuka-hiva. Both of these are very distinct from all others known. I have described Pt.pictiventris as from Nuka-hiva of the Marquesas ; but, for the reasons I give under the head of this species, I believe that locality to be an error, and that the bird in question is a native of the Samoan Islands only. To the south-west of the Marquesas lies the Pomatu archipelago, which is as yet hardly known in an ornithological sense. But one species of Ptilopus has been recorded from there, Pt. coralensis, found on Carlshoff Island. South of the Pomatu group lies the island of Rapa. Here has been procured probably the most important member of this genus, Pt. huttoni. To the west of Pomatu are the Society Islands, upon only two of which have any species of Ptilopus been procured, viz. P. chrysogaster, upon Huahaine, and Pt. taitensis in Otaheite. To the south-west of this last is Cook's Archipelago, where Pt. chalcurus has been obtained on Harvey Island. It is still doubtful if this bird is specifically distinct from Pt. coralensis of the Pomatu group. If the identity of those two could be established, it would be an interesting and important fact, since the two clusters of islands are not only separated by miles of ocean, but several distinct forms of Ptilopus are found upon the intervening archipelagos, none of which, so far as we know, are particularly related to Pt. chalcurus. Upon Rarotonga island has been procured Pt. rarotongensis; and these two species are all that have as yet been found in this group. Savage Island, lying between Cook's Archipelago and the Friendly group, contains three species-Pt. purpuratus, Pt. pictiventris and Pt. rarotongensis. Passing on to the westward we reach the Tonga Islands, among which five species of Ptilopus dwell, a number exceeded in only one of the Pacific groups, viz. the Fijis. O n Tonga-Tabou all the species occur-Pt. chrysogaster, Pt. apicalis, Pt. pictiventris, Pt. purpuratus, and Pt. perousii. Harpai contains Pt. perousii and Pt. purpuratus ; and this last has also been procured at Eua and Ninafou, the last the most northern of them all. North of the |
