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BurLER.—On the Species of the Genus Ocydromus. 213° 
Art. XXIV.—On the Species forming the Genus Ocydromus, a peculiar Group 
of brevi-pennate Rails. By WarrER L. Buter, C.M.G., Se.D., F.L.S. 
(Read before the Wellington Philosophical Society, 19th January, 1878.] 
Aurnover as a group the limits of the genus Ocydromus are sufficiently well 
defined, considerable difficulty has been experienced in determining the 
species. Every naturalist who has studied the subject appears to have 
arrived at some different conclusion as to the number of constant forms; 
and where the variances as to size and plumage are so well maintained it is 
difficult to avoid drawing specific distinctions. If, however, it can be shown 
that all these extreme forms graduate in a series, or, in other words, run 
into one another, it becomes impossible to find any fixed aberrant characters. 
Without professing to be able yet to place the matter beyond all dispute, 
I venture to think that the series of specimens which I have the honour 
to exhibit this evening affords pretty strong evidence that several of the 
so-called species in the South Island must be united under the name of 
Ocydromus australis, 
In my “ Birds of New Zealand," I admitted only three well-ascertained ` 
species as inhabiting New Zealand—namely, O. earli, O. australis, and O. 
fuscus. I mentioned in the introduction to that work that, although Dr. 
Finsch recognized a fourth (O. troglodytes, Gmel.), I was unable to draw 
any specific line. Nevertheless, I pointed out very fully, in my account 
of the South Island wood-hen, the great variation both as to size and 
markings which that species exhibits, especially among birds from 
different localities. 
Captain Hutton, in an article on the New Zealand Wood-hens, read 
before this Society* in September, 1873, agreed with Dr. Finsch in 
admitting O. troglodytes, and added two more species of his own under the 
names of O. hectori and O. finschi. He further described a “variety or 
immature" example of this last-named species, which he suggests may 
** possibly be identical with Gallirallus brachypterus, Lafr.” 
Dr. Finsch, in a paper! written the year following, professes to identify 
Ocydromus troglodytes with the O. australis of my text, page 170, but not 
the plate; of O. hectori he remarks, “I consider this a good species after 
having compared a typical specimen ;” and of O. finschi he says that, 
having examined the type, he considers it a good species, although not 
without some suspicion that it may prove to be a variety of O. fuscus. He 
confuses Ocydromus australis, Sparrm., with the well-known O. earli; and 
with respect to the latter in Hutton’s list, he makes the following singular 
statement :—‘ Dr. Buller, in his great work, unfortunately does not mention 
* u Trans. N.Z. Inst.,” VIL, p. 110. t “ Trans. N.Z. Inst.,” VIL, p. 226. 
