802 EODENTIA 



smaller than the others. First lower molar with six paired 

 tubercles and a median anterior loop nearly as large as median 

 posterior tubercle. Second lower molar with four paired 

 tubercles and a small median posterior tubercle. Third molar 

 with two paired tubercles essentially like those of the other 

 teeth, but with posterior median tubercle slightly larger than 

 either of the paired tubercles. The relative size of the three 

 teeth is indicated by the number of pairs of tubercles. Outer 

 margin of w(, and m., with a narrow ledge bearing two or three 

 minute terete cusps. The ledges and cusps are variable in their 

 degree of development ; usually they are more evident in m^ 

 than in m^ ; in m^ there are usually two at outer margin of 

 second outer main tubercle, and a third somewhat better 

 developed at margin of postero-external main tubercle ; in m^ the 

 most constant supijlemental cusp is that which lies at outer 

 base of antero-external main tubercle ; behind this there are 

 usually no distinct supplemental cusps, though one or two are 

 occasionally present. 



Bemarks. — This is the most abundant and most universally 

 distributed of European mammals. Except in cities, at the 

 extreme north, on the highest mountains, and perhaps in some 

 parts of the Mediterranean region,* it is probably everywhere 

 more numerously represented in individuals than any other 

 species. Adults are readily distinguishable from the house 

 mouse by their brighter colour, larger ear and longer hind foot ; 

 but at all ages and in all conditions of pelage the structure of 

 the teeth and the absence of supplemental tubercles to all of the 

 pads on palm and sole differentiate it from all members of the 

 genus Mus. The only European mammal with which Apodenms 

 sylvaticus is likely to be confused is A. JlavicolUs. Detailed 

 comparisons of the two animals will be found undei- the latter 

 species. 



Throughout the greater part of its range, from Ireland to 

 Roumania, and from northern Scotland and central Scandinavia 

 to Switzerland and the plains of south-western France, Apodemus 

 sylvaticMs is represented by its typical form, small sized and rich 

 in colour, the back in adults in fresh pelage usually with at 

 least a trace of russet. In the Pyrenees, Asturias and Portugal 

 occurs a larger race, which, however, retains the bright colour 

 of true sylvaticus. This tendency toward larger size is shown 

 throughout the Mediterranean region, though a small race 

 occurs on the island of Crete. Unlike the Pyrenean-Asturian 

 form the true Mediterranean races are all pale, with yellowish 

 or greyish tints predominating to the exclusion of russet. Along 

 the Mediterranean coast of France, and in northern Italy lies 



* In the vicinity of Elche, Alicante, Spain, I found Apodemus sylvaticus 

 much less numerous than Mus spicilegus, and practically coniined to 

 ravines and river banks, while the smaller animal was abundant every- 

 where. 



