668 R0DENTIA 



member of the sub-genus is Microtus arvalis, fully adult 

 individuals may be recognized by their larger size, more hairy 

 ears, larger tubercles on sole, and by the browner, less buffy 

 coloration, the dark and light elements of which are more 

 coarsely mixed. As might be anticipated from the animal's wide 

 range, numerous local forms have been developed. Seven of 

 these are now known. 



Microtus agrestis agrestis Linnseus. 



1761. Mus agrestis Linnaeus, Fauna Sueeica, 2nd ed., p. 11 (Upsala, 



Sweden). 

 1766. [Mas'] gregarius Linnseus, Syst. Nat., i, 12th ed., p. 84 (Germany 



and Sweden). 

 1792. Mus arvalis nigricans Kerr, Anim. Kingd., p. 239 (Renaming of Mus 



1820. Lemmus arvalis Nilason, Skand. Fauna, I, p. 189 (not Mus arvalis 



Pallas). 

 1841. Arvicola agrestis de Selys-Longchamps, Bull, de l'Acad. Royale des 



Sci. des Arts et Belles-Lettres de Bruxelles, vm, pt. 2, p. 236. 

 1844. L[emmus~\ insularis Nilsson, Ofversigt af Kongl. Vetensk.-Akad. 



Forhandl., Stockholm, i, p. 34, March 20, 1844. (Ostgotha 



Skargard, Sweden.) 

 1857. Arvicola agrestis a. Blasius, Saugethiere Deutschlands, p. 369 (part). 

 1884. Microtus agrestis Lataste, Ann. Mus. Giv. Stor. Nat. Genova, xx, 



p. 255, March, 1884. 

 1896. Microtus agrestis Barrett-Hamilton, Proc. Zool. Soc, London, p. 602. 

 1910. Microtus agrestis Trouessart, Faune Mamm. d'Europe, p. 175 (part). 



Type locality. — Upsala, Sweden. 



Geographical distribution. — Scandinavian Peninsula ; eastward 

 into Finland. Exact limits of range not known. 



Diagnosis. — Size large (hind foot, 18 to 19 '4 mm.; condylo- 

 basal length of skulls in largest individuals, 27 to 28 ■ 5 mm.) ; 

 skull with brain-case tending to be relatively short, the distance 

 from condyle to back of interorbital constriction usually about 

 equal to zygomatic breadth ; first upper molar rarely with small 

 postero-internal loop ; general colour above a light bister, below 

 greyish with faint buffy cast. 



Colour. — Hairs of upper parts slate-black basally, those of 

 underfur tipped (about 2 mm.) with a dull buff intermediate 

 between the ochraceous-buff and cream-buff of Ridgway (the 

 extreme tips often dark), the longer hairs iridescent black. The 

 general effect is a clear brown, rather lighter than bister along 

 back and becoming somewhat buffy on sides, everywhere rather 

 conspicuously " lined " by the longer black hairs. Underparts 

 well-defined light silvery grey faintly washed with buffy and 

 darkened irregularly by the slaty bases of the hairs. Feet and 

 under surface of tail concolor with belly ; dorsal surface of tail 

 dark brown. In winter the colour above is usually not so dark 

 as in summer, and the " lining " on back is less conspicuous ; 



