The nest is similar in size to that of a Crow, it is composed outwardly of sticks, and lined with strips of stringy bark, leaves, &c.; the eggs, which are two, and sometimes three in number, vary so much in colour, that they are seldom found alike, even in the same nest; they are also longer or of a more oval shape than those of the generality of Falcons; the prevailing colour is,—the ground buffy white, covered nearly all over with reddish brown: in some specimens an entire wash of this colour extends over nearly half the egg, while in others it is blotched or freckled in small patches over the surface generally: their medium length is two inches and two lines, and breadth one inch and six lines. Crown of the head ferruginous brown, with a fine black line down the centre of each feather; a streak of black from the base of the lower mandible down each side of the cheek; ear-coverts brown; throat, chest, centre of the abdomen, and under tail-coverts pale buff, with a fine line of brown down each side of the shaft of every feather; flanks ferruginous, each feather crossed with spots of buffy white; thighs dark brown, crossed like the flanks but with redder spots; centre of the back reddish brown; scapularies and wing-coverts brown, crossed with conspicuous bars and spots of ferruginous; tail brown, crossed with ferruginous bars, and tipped with light brown; primaries blackish brown, margined on their inner webs with large oval-shaped spots of buff; bill light lead colour, passing into black at the tip; cere and orbits pale bluish lead colour; irides very dark brown; feet very light lead-colour. The figures represent the two sexes of the natural size. [Illustration: IERACIDEA OCCIDENTALIS: _Gould_. _J. Gould and H. C. Richter del et lith._ _C. Hullmandel Imp._ ] IERACIDEA OCCIDENTALIS, _Gould_. Western Brown Hawk. _Ieracidea occidentalis_, Gould in Proc. of Zool. Soc., June 25, 1844. _K̏ar-gyne_, Aborigines of the lowland and mountain districts of Western Australia. Hitherto ornithologists, and among them myself, have regarded the Common Brown Hawks, which occur so numerously in collections from Australia, as referrible to one and the same species,—an opinion founded principally upon the circumstance of the members of this genus being subject to a greater number of changes of plumage from youth to maturity than any other; observation, however, aided by dissection, and that too of very many examples, and at all seasons of the year, has convinced me that there are two species, which appear to occupy opposite portions of the continent; the present bird, as its name implies, being confined to the western, and the _I. Berigora_ to the eastern. Both species are occasionally found in South Australia, but the latter is the most abundant, and here it would seem that they inosculate.