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Show 1900.] MUS SYLVATICUS AND ITS ALLIES. 389 here advocated, namely, that it does not add to the difficulties of student of the geographical distribution of mammals in its broadest and widest sense. The numerous modern species, although they may be of the greatest interest to the student of the fauna of a single or of a particular group of countries, cannot but be a source of perplexity to the naturalist, wiiose aim it is to regard the mammals of the world as a whole. To the latter the liberal and intelligent use of trinomials must be a boon, rendering possible as it does a ready comprehension of the origin and relationship of any particular local or representative form which he may have before him. But, after all, the main object of our study should be the variations of the animal or group of animals dealt with. Provided that this be our aim, the exact method we employ is surely of subsidiary importance. No method that does or can exist, unless it be diagrammatic or pictorial, is capable of fully or satisfactorily exhibiting the variations which have to be dealt with. Distribution.-The distribution of Mus sylvaticus, speaking of it in abroad sense as including all its subspecies, is, as I have already pointed out1, almost cotermiuous with the limits of the Paiaearctic Eegion, in which it is probably as widely spread as most other mammals, since it seems to be comparatively regardless of the influence of temperature and is found far up the slopes of the mountains. Thus Dr. G. Badde2 met with it almost everywhere in his journeys in Southwestern Siberia, and it is especially common on the middle Amoor. He remarks that there can be no doubt that it is found, at lea^t locally, in the regions lying between wooded Dauria and Lake Baikal, at all events in the grassy country, but that it is absent from the high steppes of Mongolia. In these regions it avoids swampy and shaded localities, but loves sunny slopes with sparsely distributed high woods, where it gladly gathers the dry windfalls for its nest. With these exceptions, to which must be added the deserts and arctic tundras, it is equally at home in all the countries between the eastern coast-line of China and the Atlantic sea-board of Ireland or Portugal. It has reached nearly all the outlying portions of the Eegion, such as Morocco, Algeria, Palestine, Corsica, Sicdy, the Balearic's, the Channel Islands, Great Britain, the Isle of Man, Ireland, the Scotch Islands 3 (such as the Inner Hebrides, where it is abundant on all the islands), the Outer Hebrides (including even remote St. Kilda4), the Shetlands, and Iceland, and in the last locality its local representative, if indigenous, is the only species of mammal that is so. On the other hand, I have seen no specimen from any of the Japanese islands, where, however, I believe, that on Nippon Mus argenteus is its modified 1 Proc Zool. Soc. Feb. 7, 1899, p. 82. 2 ' Reisen im Siiden von Ost-Sibirien in den Jahren 1855-1859 incl.' Band i. pp. 180-182 (1862). 3 J. A. Harvie-Brown & T. B. Buckley: ' Vertebrate Fauna of Argyll and the Inner Hebrides,' 1892, p. 38. 4 I have as yet seen no specimen from either the Orkneys or the Faroes. It doubdess occurs on the former; the case of the latter will be discussed below. P R O C ZOOL. Soc-1900, No. XXVI. 26 |