THE HOUSE MOUSE 647 



Geographical variation: — Of the seven European forms of Mus 

 recognised by Miller, two only are referred by him to M. musculus, 

 viz. : M. m. musculus, described above, and M. m. azortcus, Schinz, 

 inhabiting the Azores and the Mediterranean region. The latter 

 sub-species is distinguished from the typical form by its lighter and 

 yellower back, and its buffy grey, instead of dusky grey belly. It 

 may be regarded merely as a phase of coloration appropriate to a 

 sunnier climate, and the gap between it and the dusky indoor animal 

 of northern countries is, at least, partly bridged by our more pallid out- 

 door individuals. Winge {op. cit., 89) states that at present the wild- 

 coloured race is the common one in Denmark ; he adds that formerly 

 the dusky indoor form has certainly been preponderant. Two insular 

 forms, M. muralis and M. fceroensis, from St Kilda and the Fseroes 

 respectively, are accorded full specific rank by Miller; these are dis- 

 cussed below. 



The remaining three European members of the genus are treated 

 by Miller as sub-species of M. spicilegus, Petenyi, described from 

 Hungary. This species differs from M. musculus in its smaller size 

 (condylo-basal length of skull rarely attaining 21 ; hind foot usually 

 between 15 and 17 mm.); in having the tail nearly always noticeably 

 shorter than the head and body, the under parts whitish and sharply 

 contrasted with the flanks, and the notch of the upper incisor less 

 developed. The typical form, characterised by its clear greyish-brown 

 upper parts, ranges from the northern part of the Balkan Peninsula to 

 the Baltic, and westwards into southern Sweden. Its representative in 

 central and southern Spain is M. s. hispanicus. Miller, in which the 

 dorsal colour is " buffy, or pale buffy grey." The third sub-species is 

 M. s. lusitanicus. Miller, known only from Cintra, Portugal ; in this the 

 upper parts are brownish-grey, and show a decided tinge of russet. 

 Both Thomas {Zoologist, 1896, 137), who first discovered M. spicilegus 

 in Portugal and afterwards in the Balearic Islands, and Miller 

 {Catalogue, Syy) regard this species as truly indigenous to the Mediter- 

 ranean region. It leads a perfectly wild life in fields, scrub, and open, 

 dry forest, and it thus affords in station and coloration a close parallel 

 to Eptmys rattus frugivorus. It appears to be the natural representa- 

 tive in Europe of M. spretus, Lataste,^ from North Africa ; and 

 Thomas states that " like the Mungoose and the Genet, it forms part 



282, iii,, I (Japanese Waltzing Mice crossed with European albinos) ; Durham, Rep. 

 Evol. Comm. Roy. Soc, iv., 41, 1908 ; Hagedoorn, Univ. California Pub. Physiol., 

 lii., 1909, 95 ; Zeitsch. indukt. Abstammungslehre, Berlin, 6, 19 12, 97 ; and Little, 

 Washington Carnegie Inst., Pub. No. 179, 19 13, 11. 



^ Actes Soc. Linn., Bordeaux, 1883, 17 ; but later {Cat. crit. Mamm. Tunis, Paris, 

 1887, 22) Lataste himself recognised that M. spretus "is, perhaps, only a very 

 aberrant variety of the House Mouse." 



