This is the least of the Australian Owls belonging to that section of the group to which the generic term of _Strix_ has been restricted; it is also the one most generally distributed. I observed it in almost every part of New South Wales that I visited; it is a common bird in South Australia, and I have also seen specimens of it from Port Essington. It has not yet been found in the colony of Swan River, nor can it be included in the fauna of Van Diemen’s Land. Although good specific differences are found to exist, it is very nearly allied to the Barn Owl (_Strix flammea_) of our own island, and, as might be naturally expected, the habits, actions and general economy of the two species are as similar as is their outward appearance: mice and other small mammals, which are very numerous, are preyed upon as its natural food. To attempt a description of its noiseless flight, its mode of capturing its prey, or of its general habits, would be merely to repeat what has been so often and so ably written relative to the Barn Owl of Europe. Although the plumage of youth and that of maturity do not differ so widely in this species as in the other Australian members of the genus, the fully adult bird may always be distinguished by the spotless and snowy whiteness of the breast, and by the lighter colouring of the upper surface. Facial disc white, margined with buff; upper surface light greyish brown tinged with yellow, very thickly and delicately pencilled with spots of brownish black and white; wings pale buff lightly barred with pale brown, marked along the outer edge and extremities with zigzag pencillings of the same, each primary having a terminal spot of white; tail resembles the primaries, except that the terminal white spot is indistinct, and the outer feathers are almost white; under surface white, sparingly marked about the chest and flanks with small brownish dots; legs and thighs white; bill horn-colour; feet yellowish. The figure is of the natural size. [Illustration: ATHENE BOOBOOK. _J. Gould and H. C. Richter del et lith._ _Hullmandel & Walton Imp._ ] ATHENE BOOBOOK. Boobook Owl. _Strix Boobook_, Lath. Ind. Orn. Suppl., p. xv. no. 9.—Shaw, Gen. Zool., vol. vii. p. 262. _Boobook Owl_, Lath. Gen. Hist., vol. i. p. 362. no. 66.—Id. Gen. Syn. Suppl., vol. ii. p. 64. _Noctua Boobook_, Vig. and Horsf. in Linn. Trans., vol. xv. p. 188. _Athene Boobook_, Gould in Syn. Birds of Australia, Part I. _Buck-buck_, Aborigines of New South Wales. _Goȍr-goȍr-da_, Aborigines of Western Australia. _Mȅl-in-de-ye_, Aborigines of Port Essington. _Koor-koo_, Aborigines of South Australia. _Brown_ or _Cuckoo-Owl_ of the Colonists.