representative of _Glaucidium passerinum_ to the western regions,[9] and of _Strix flammea_ to the very southern and maritime portions of the United States, the European representatives of both species being generally distributed throughout that continent. On the other hand, the northwest-coast race of our _Scops asio_ (_S. kennicotti_) seems to be nearly identical with the Japanese _S. semitorques_ (Schlegel), which is undoubtedly referrible to the same species. As regards their plumage, the Owls differ most remarkably from the Hawks in the fact that the sexes are invariably colored alike, while from the nest to perfect maturity there are no well-marked progressive stages distinguishing the different ages of a species. The nestling, or downy, plumage, however, of many species, has the intricate pencilling of the adult dress replaced by a simple transverse barring upon the imperfect downy covering. The downy young of _Nyctea scandiaca_ is plain sooty-brown, and that of _Strix flammea_ immaculate white. In many species the adult dress is characterized by a mottling of various shades of grayish mixed with ochraceous or fulvous, this ornamented by a variable, often very intricate, pencilling of dusky, and more or less mixed with white. As a consequence of the mixed or mottled character of the markings, the plumage of the Owls is, as a rule, difficult to describe. In the variations of plumage, size, etc., with differences of habitat, there is a wide range, the usually recognized laws[10] applying to most of those species which are generally distributed and resident where breeding. Of the eight species common to the Palæarctic and Nearctic Realms, all but one (_Otus brachyotus_) are modified so as to form representative geographical races on the two continents. In each of these cases the American bird is much darker than the European, the brown areas and markings being not only more extended, but deeper in tint. The difference in this respect is so tangible that an experienced ornithologist can instantly decide to which continent any specimen belongs. Of the two cosmopolitan species one, _Otus brachyotus_, is identical throughout; the other is modified into geographical races in nearly every well-marked province of its habitat. Thus in the Palæarctic Realm it is typical _Strix flammea_; in the Nearctic Realm it is var. _pratincola_; while Tropical America has at least three well-marked geographical races, the species being represented in Middle America by the var. _guatemalæ_, in South America by var. _perlata_, and in the West Indies by the var. _furcata_. The Old World has also numerous representative races, of which we have, however, seen only two, namely, var. _javanica_ (Gm.), of Java, India, and Eastern Africa, and var. _delicatula_ (Gould) of Australia, both of which we unhesitatingly refer to _S. flammea_.[11]