OCYDROME, a word formed from Ocydromus, meaning "swift-runner," and suggested by Wagler in 1830 as a generic term for the New-Zealand bird called in the then unpublished manuscripts of the elder Forster Rallus troglodytes, and so designated in 1788 by Gmelin, who knew of it through Latham's English description. Wagler's suggestion has since been generally adopted, and the genus Ocydromus is accepted by most ornithologists as a valid group of Rallidx ; but the number of species it contains is admittedly doubtful, owing to the variability in size and plumage which they exhibit, and their correct nomenclature must for the present be considered uncertain. Mr Buller in his Birds of New Zealand identifies the " Wood-hen," observed in great abundance on the shores of Dusky Bay in 1773 by Cook and his companions on his second voyage, with the Gallirallus fuscus described and figured by Du Bus in 1847, and accordingly calls it O. /mats; but it cannot be questioned that the species from this locality - which appears to have a somewhat limited range in the Middle Island,1 and never to be met with far from the sea-coast, where it lives' wholly on crustaceans and other marine animals - is identical with that of the older authors just mentioned. In 1786 Sparrman, who had also been of Cook's company, figured and described as Rallus australis a bird which, though said by him to be that of the southern coast of New Zealand, differs so much from the R. troglodytes as to compel a belief in its specific distinctness ; and indeed his species has generally been identified with the common " Weeka" of the Maories of the Middle Island, which can scarcely be the case if his statement is absolutely true, since the latter does not appear to reach so far to the southward, or to affect the sea-shore. It may therefore be fairly inferred that his subject was obtained from some other locality. The North Island of New Zealand has what is allowed to be a third species, to which the name of Ocydromus earli is attached, and this was formerly very plentiful ; but its numbers are rapidly decreasing, and there is every chance of its soon being as extinct as is the species which tenanted Norfolk Island on its discovery by Cook in 1774, and was doubtless distinct from all the rest, but no specimen of it is known to exist in any museum.' Another species, 0. sylvestris, smaller and lighter in colour than any of the rest, was found in 1869 to linger yet in Lord Howe's Island (Proc. Zool. Society, 1869, p. 472, pl. xxxv.). Somewhat differing from Ocydromus, but apparently very nearly allied to it, is a little bird peculiar, it is believed, to the Chatham Islands (Ibis, 1872, p. 247), and now regarded by Captain Hutton as the type of a genus Cabalus under the name of C. modestus, while other naturalists consider it to be the young of the rare Rallus dieffenbacici. So far the distribution of the Ocydromine form is wholly in accordance with that of most others characteristic of the New-Zealand sub-region; but a curious exception is asserted to have been found in the Gallirallus lafresnayanus of New Caledonia, which, though presenting some structural differences, has been referred to the genus Ocydromus.

The chief interest attaching to the Ocydromes is their inability to use in flight the wings with which they are furnished, and hence an extreme probability of the form becoming wholly extinct in a short time. Of this inability there are other instances among the Rallidx (see MOORHEN, vol. xvi. p. 808); but here we have coupled with it the curious fact that in the skeleton the angle which the scapula makes with the coracoid is greater than a right angle, a peculiarity shared only, so far as is known, among the Carinatae by the Dodo. The Ocydromes are birds of dull plumage, and mostly of retiring habits, though the common species is said to show great boldness towards man, and, from the accounts of Cook and the younger Forster, the birds seen by them displayed little fear. It is also declared that they will interbreed with common poultry, and more than one writer vouches for the truth of this extraordinary statement. It is to be hoped that the naturalists of New Zealand will not allow the form to become extinct if any effectual means can be taken to perpetuate it ; but, should that fate be inevitable, it at least behoves the present generation to see that every possible piece of information concerning the birds be recorded, and every possible preparation illustrating their structure be made, while yet there is time ; for, though much has been written on the subject, it is obvious from one of the latest papers (Trans. Hew Zealand Institute, x. p. 213) that there is still more to be learned, some of which may throw further light on the affinities of the birds of the extinct genus Aptornis. (A. N.)