MICROTUS 669 



occasionally the shoulders are suffused with grey ; tail more 

 noticeably bicolor than in summer, and underparts of body more 

 silvery. 



Sktill and teeth. — Skull large, that of old individuals becoming 

 strongly angular and developing a knife-like ridge in interorbital 

 region. Brain-case showing no tendency to lengthen out 

 posteriorly, the distance from back of interorbital constriction to 

 posterior surface of condyle barely eijual to zygomatic breadth. 

 Teeth with no special peculiarities ; m^ rarely"' showing any trace 

 of postero-internal loop. 



Measurements. — Average and extremes of five adults from 

 Upsala, Sweden: head and body, 121-8 (118-127); tail, 35-8 

 (33-38); hind foot, 18 '4 (18-19). Average and extremes of 

 five adults from Medstugan, Jemtland, Sweden : head and body, 

 126-8(123-132); tail, 35-6 (31-39) ; hind foot, 18-6 (18-19-4). 

 Adult male from Porsanger, Norway : hind foot, 18. For cranial 

 measurements see Table, p. 676. 



Specimens examined. — Seventy-three, from the following localities : — 

 Norway: Porsanger, 1 (U.S.N.M.) ; Brekkebygden, Trondhjem, 2; 

 Molmen, Kristiansamt, 4 ; Holaaker, Kristiansamt, 2 ; Hjerkin, Kris- 

 tiansamt, 4 ; Sundal Fjeld, 1 ; Alverstrom, Bergen, 2 (U.S.N.M.) ; Bergen, 2 

 (U.S.N.M.); Graven, Bergen, 3 (U.S.N.M.); Gausdal, 3 (B.M. and 

 U.S.N.M.) ; Asker, Kristiania, 1 (U.S.N.M.) ; Smaalenene, 1 (U.S.N.M.). 



Sweden: Medstugan, Jemtland, 11 ; Upsala, 34 (B.M. and U.S.N.M.) ; 

 near Stockholm, 2. 



R. J. Cuninghame 98. 5. 2. 6-9. 



(c & p). 

 R. J. Cuninghame 98. 2. 28. 6-7. 



(c & p). 

 G. Barrett-Hamilton 11. 1. 2. 46-47. 



(c & p). 

 E. Lort Phillips 94. 10. 22. 1. 



(c & p). 

 Ohristiania Museum 93. 3. 1. 12. 



(E). 



Miller Collection. 7. 7. 7. 45.37. 



R. J. Cuninghame 8. 8. 9. 80-37. 



(c & p). 



Baron E. de S61ys- 45. 7. 5. 12. 



Lougchamps (p). 



Lord Lilford (p). 0. 5. 15. 2-5. 



Prof. Sundevall (c). 45. 10. 25. 5-6. 



MiCROTus AGRESTis ExsuL Miller. 



1908. Microtus agrcstis cxsul Miller, Ann. and Mag. Nat. Hist., 8th ser., i, 



p. 201, February, 1908. Type in British Museum. 



1909. Microtus agrestis insul Lydekker, Zool. Record, xlv (1908), Mamm., 



p. 74 (Accidental renaming of exsul). 



1910. Microtus agrestis exsul Trouessart, Faune Mamm. d'Europe, p. 176. 



Ty2}e locality. — North Uist, Hebrides, Scotland. 

 Geograplnccd distribution. — North and South Uist, Hebrides. 



* In a little more than five per cent, of the specimens examined. 



