326 arvicolidjE. 



above the fur, and are lined with fine hairs, whereas in 

 A. arvalis the inside of the conch is naked. The colour 

 is greyish-brown, the flanks being more or less tinged 

 with reddish or yellowish ; the under parts are pale grey 

 or dirty white, and the feet are dusky. The young are 

 darker in colour than the adults. The tail measures 

 about one-third the length of the body, is sparingly clad 

 with hair, and is obscurely bi-coloured, being brown 

 above and greyish beneath. 



In the skull the frontal portion is much narrowed in 

 the adult animal. The second upper molar has five 

 cemental spaces and six angles, a character which, as 

 already stated, separates this species from all the other 

 European Voles ; the third has six spaces and eight 

 angles, and the first lower molar has nine spaces and 

 eleven angles. Slight variations occur in the pattern of 

 these teeth, but they are not constant, and are not even 

 always the same on both sides of the same skull. 



Dimensions : — 



Incli, Lines. 

 Length of the head and body . .41 



,, of the head . . . . . .12 



,, of the ears . .05 



,, of the tail . . .13^ 



Two Voles described as British have been referred to 

 this species by Blasius and other recent writers. These 

 are the A. neglecta of Thompson {Arm. and Mag. Nat. Hist. 

 1841), and the A. britannicus of De Selys Longchamps 

 {Revue ZooL, 1847) ; the characters on which their distinc- 

 tion was founded were merely external differences of tint 

 and proportions, which cannot in the least be depended 

 on in so variable and difficult a family as the Voles. 



