The nest, which is constructed of sticks and fibrous roots, is frequently built on the topmost branches of the lofty _Casuarinæ_, growing by the sides of creeks and rivers. The eggs, which are laid during the months of November and December, are usually two in number, but sometimes single; they are two inches and three lines long by one inch and nine lines broad, and are of a bluish white slightly tinged with green, the few brown markings with which they are varied being very obscure and appearing as if beneath the surface of the shell. I once found a nest of this species in the side of which had been constructed that of the beautiful little Finch called _Amadina Lathami_, and both birds sitting on their respective eggs close beside each other; and both would doubtless have reared their progenies had I not robbed the nests of their contents to enrich my collection. The Whistling Eagle presents the usual difference in the size of the sexes, but in respect to colour no variation is observable; the plumage of the young, on the contrary, as shown by the front figure on the Plate, presents a striking contrast to that of the adult, rendering it by far the handsomer bird during the first autumn of its existence. Head, neck and all the under surface light sandy brown, each feather margined with a darker colour; feathers of the back and wings brown, margined with greyish white; primaries blackish brown; tail greyish brown; cere and bill brownish white, gradually becoming darker towards the tip of the latter; legs pale bluish white; irides bright hazel. The figures represent an old and a young bird about two-thirds of the natural size. [Illustration: PANDION LEUCOCEPHALA: _Gould_ _J. Gould and H. C. Richter del et lith._ _C. Hullmandel Imp._ ] PANDION LEUCOCEPHALUS, _Gould_. White-headed Osprey. _Pandion leucocephalus_, Gould in Proc. of Zool. Soc., Part V. p. 138; and in Syn. Birds of Australia, Part III. _Yoon-dȍor-doo_, Aborigines of the lowland districts of Western Australia. _Jȍor-joot_, Aborigines of Port Essington. _Little Fish Hawk_, Colonists of New South Wales. _Fish Hawk_, Colonists of Swan River.