The sexes are so much alike in colour that it is by the greater size of the female alone that they are to be distinguished; the young, on the other hand, differ considerably from the adult. Head, neck, chest and upper part of the abdomen snow white; back, wings, lower part of the abdomen, thighs, upper and under tail-coverts rich chestnut red; first six primaries chestnut at the base and black at the tip; tail-feathers chestnut red on their upper surface, lighter beneath, the eight central feathers tipped with greyish white; irides light reddish yellow; cere pale yellowish white; orbits smoke-grey; upper mandible light ash-grey at the base, passing into sienna-yellow and terminating at the tip in light horn-colour; under mandible smoke-grey; tarsi cream-yellow, much brighter on all the large scales on the front of the tarsi and toes. The figures are those of an adult and a young bird two-thirds of the natural size. [Illustration: HALIASTUR? SPHENURUS. _J. Gould and H. C. Richter del et lith._ _C. Hullmandel Imp._ ] HALIASTUR? SPHENURUS. Whistling Eagle. _Milvus sphenurus_, Vieill. 2nde Edit, du Nouv. Dict. d’Hist. Nat., tom. xx. p. 564.—Ibid. Gal. des Ois., tom. i. p. 41. pl. 15.—Ibid. Ency. Méth. Orn., Part III. p. 1204. _Haliæetus canorus_, Vig. and Horsf. in Linn. Trans., vol. xv. p. 187.—Gould, in Syn. Birds of Australia, Part III. _Moru and Wirwin_, Aborigines of New South Wales. _En-̏na-jook_, Aborigines of the Cobourg Peninsula. _J̏an-doo_, Aborigines of the lowland districts of Western Australia. _Whistling Hawk_, Colonists of New South Wales. _Little Swamp Eagle_, Colonists of Western Australia.