Van Diemen’s Land is the native country of this Owl, a species distinguished from all the other members of the genus _Strix_, as now restricted, by its great size and powerful form; few of the Raptorial birds, in fact, with the exception of the Eagles, are more formidable or more sanguinary in disposition than the bird here represented. Forests of large but thinly scattered trees, skirting plains and open districts, constitute its natural habitat. Strictly nocturnal in its habits, as night approaches it sallies forth from the hollows of the large gum-trees, and flaps slowly and noiselessly over the plains and swamps in search of its prey, which, as is the case with the other members of the genus, consists of rats and small quadrupeds generally, numerous species of which abound in the country wherein it is destined by nature to dwell. I regret that the brevity of my stay in Van Diemen’s Land did not admit of sufficient opportunities for observing this bird in its native haunts, and of making myself acquainted with the various changes which take place in the colouring of its plumage. Much variety in this respect exists among the specimens in my collection; occasioned not so much by a difference in the form of the markings, as by a difference in the hue of the wash of colour which pervades the face, neck, under surface and thighs. In some specimens the face, all the under surface and the thighs are deep rusty yellow; in others the same parts are slightly washed with buff, while others again have the face of a dark reddish buff approaching to chestnut, and the under surface much lighter; I have also seen others with the facial feathers lighter than those of the body, and, lastly, some with the face and all the under surface pure white, with the exception of the black spots which are to be found in all. Whether the white or the tawny plumage is the characteristic of the adult, or whether these changes are influenced by season, are points that might be easily cleared up by persons resident in Van Diemen’s Land, and I would invite those who may be favourably situated for observation to fully investigate the subject and make known the results. I found the white variety far less numerous than the others; and so much smaller in size, as almost to induce a belief that they were distinct. The sexes differ very considerably in size, the female being by far the largest, and in every way more powerful than the male: the stroke of her foot and the grasp of her talons must be immediate death to any animal, from the size of the little Opossum Mouse to the largest of the Kangaroo-rats, upon which latter animals it is probable that future research will prove it sometimes subsists.