470 MURIDAE—LOCALLY EXTINCT VOLES 
Somersetshire, and in the later “middle terrace” deposits of 
the Thames at Crayford and Erith. 
Remains of several small species of A/zcrotus have been 
found in the late pliocene Forest Bed of Norfolk. In their 
dental characters these recall such existing forms as JZ. arvalis 
and ratticeps, or the pleistocene anglicus, but they all have 
peculiarities which show that they belong to extinct types which 
probably have little real connection with those of the late 
pleistocene or recent faunas of western Europe (Forsyth Major, 
Proc. Zool. Soc., 18th February 1902, 107; Hinton, Proc. Geol. 
Assot., Xxi., 490, 1910). One of these Forest Bed forms, 
M. nwvalordes (Forsyth Major, of. czt., 106, Fig. 19), may possibly 
be a forerunner of Chzoxomys. 
The sub-genus Chionomys was formed by Miller (Aun. and 
Mag. Nat. Fost., January 1908, 97; based on Arvicola nivalis 
of Martins, Revue Zoologique 
(Paris), 1843, xix., 87) for the 
mice usually known as the “Snow 
Voles,” and formerly referred to 
a single species (zzvalzs). Miller 
now recognises three European 
Fic. 76.—Clishomys nivalis: A, left _m,, Species; these,wor their alliesaue 
B, left »; crown view ; 73 times life found from the Pyrenees to Asia 
size. (Drawn by M. A. C. Hinton.) : , C 
Minor and Transcaucasia, mostly 
in mountains. They have rather long tails, usually of whitish 
colour, full soft fur, and a very characteristic slaty-grey upper 
side. The skull has a broad, flat, rather smooth brain-case, 
wide inter-orbital region, inconspicuous temporal ridges, and 
the hinder palate sculptured in low relief with a broad median 
septum. °* has only two folds and three salient angles on 
either side; in mm, the anterior loop is small, broad, and 
crescentic, 
Chronomys has been identified from numerous continental 
deposits of Pleistocene age, as in Lombardy, and at Parignana, 
near Pisa, Italy (see Forsyth Major, A?¢tz. Soc. Scz. Nat. Ltal,, 
1872, xv., 378); in the island of Palmaria, near Spezzia; in 
French Switzerland; in Bohemia and Moravia (Nehring, 
Woldrich). 
In Britain, disregarding M/Z. nzvalordes of the Forest Bed 

