470 MURID^— LOCALLY EXTINCT VOLES 



Somersetshire, and in the later "middle terrace" deposits of 

 the Thames at Crayford and Erith. 



Remains of several small species of Microtus have been 

 found in the late pliocene Forest Bed of Norfolk. In their 

 dental characters these recall such existing forms as M. 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, 1 8th February 1902, 107 ; Hinton, Proc. Geol. 

 Assoc, xxi., 490, 19 10). One of these Forest Bed forms, 

 M. nivaloides {Forsyth Major, op. cit., 106, Fig. 19), may possibly 

 be a forerunner of Chionomys. 



The sub-genus Chionomys was formed by Miller {Ann. and 

 Mag. Nat. Hist., 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 {nivalis). Miller 

 ^ now recognises three European 



Fig. n(>.-chu,nomy^ mvaiis : A, left m^; species ; these. Or their allies, are 

 B, left nfl ; crown view ; 74 times life found from the Pyrenees to Asia 



size. (Drawn by M. A. C. Hinton.) n/r- j 'n • ^i 



' Mmor and 1 ranscaucasia, 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, m^ has only two folds and three salient angles on 

 either side ; in m^ the anterior loop is small, broad, and 

 crescentic. 



Chionomys has been identified from numerous continental 

 deposits of Pleistocene age, as in Lombardy, and at Parignana, 

 near Pisa, Italy (see Forsyth Major, Atti. Soc. Sci. Nat. Ital, 

 1872, XV., 378); in the island of Palmaria, near Spezzia ; in 

 French Switzerland ; in Bohemia and Moravia (Nehring, 

 Woldrich). 



In Britain, disregarding M. nivaloides of the Forest Bed 



