1900.] MUS SYLVATICUS AND ITS ALLIES. 389 



here advocated, namely, that it does not add to the difficulties of the 

 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, whose 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 importauce. No method that does or cau 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 Mvs sylvaticus, speaking of it 

 in a broad sense as including all its subspecies, is, as I have already 

 pointed out 1 , almost coterminous with the limits of the Palsearctic 

 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 f'ouud far up the slopes of the 

 mountains. Thus Dr. Gr. Eadde 2 met with it almost everywhere in 

 his journeys in South-western Siberia, and it is especially common 

 on the middle Amoor. He remarks that there can be no doubt 

 that it is found, at least 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. Kilda 1 ), the Shetlands, 

 and Iceland, and in the last locality its local representative, if indi- 

 genous, 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 Mas aryenteus is its modified 



1 Proc Zool. Soc. Feb. 7, 1899, p. 82. 



2 ' Reisen im Siiden von Ost-8ibirien in den Jahren 1855-1859 inch' 

 Band i. pp. 180-182(1862). 



3 J. A. Harvie-Brown & T. E. 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 tlio Faroes. It 

 doubtless occurs on the former ; the case of the latter will be discussed, 

 below. 



Pkoc. Zool. Soc— 1900, No. XXVI. 26 



