The sexes are so precisely similar in plumage, and differ so little in size, that dissection must be resorted to to distinguish the one from the other. Head and back of the neck brownish grey; back, wing-coverts, rump, upper tail-coverts, margins of the primaries, and the margins of the basal half of the tail-feathers bright olive-green; primaries and tail-feathers brown, the latter becoming much darker towards the extremity; under surface white; sides and vent olive-yellow; irides wood-brown; upper mandible greenish grey; lower mandible white; feet blackish grey. The Plate represents the two sexes of the natural size. [Illustration: SMICRORNIS BREVIROSTRIS: _Gould_. _J. Gould and H. C. Richter del et lith._ _Hullmandel & Walton Imp._ ] SMICRORNIS BREVIROSTRIS, _Gould_. Short-billed Smicrornis. _Psilopus brevirostris_, Gould in Proc. of Zool. Soc., Part V. p. 147. _Geah-ter-but_, Aborigines of the mountain districts of Western Australia. Until more information has been acquired respecting the members of this genus, I shall regard the species from Swan River and New South Wales as the same, although some trivial differences exist in the examples from those distant localities. It is a constant inhabitant of the leafy branches of the _Eucalypti_, and resorts alike to those of a dwarf stature and those of the loftiest growth. While searching for insects, in which it is incessantly engaged, it displays all the scrutinizing habits of the _Pari_ or Tits, clinging about the finest twigs of the outermost branches, prying underneath and above the leaves and among the flowers, uttering all the while or very frequently a low simple song. I found it abundant in every part of South Australia I visited, particularly in the neighbourhood of Adelaide and in the gulleys of the ranges skirting the belts of the Murray; in New South Wales it was frequently seen at Yarrundi, and other parts of the Upper Hunter district. Mr. Gilbert states that in Western Australia he only met with it in the York district, that it was always seen on the branches of trees, where it feeds on larvæ and small insects, that its flight was of very short duration, merely flitting from tree to tree, and that its note is a weak twitter, a good deal resembling that of the _Acanthiza chrysorrhœa_.