BOCALLEY EXTINGI VOLES 469 
‘ 
Wellikii-Ustjug, north central Russia) is a large, long-skulled 
mouse with relatively heavy teeth (condylo-basal length of skull 
to 30 mm., the condylo-basal length about twice the zygomatic 
breadth; hind foot 19 to 21); mm, resembles that of JV. 
anglicus in having only three outer salient angles, but the 
fourth outer angle is still more reduced and the third outer 
fold is shallow, so that there are only four closed triangles, the 
fifth opening more or less widely into the anterior loop (Fig. 75). 
me has usually a small fourth outer angle ; and m, has the third 
outer angle distinct though small. 
MM. ratticeps is found at the present time in northern Eurasia, 
from Skandinavia (in mountains and lowlands) to some point 
in Siberia, and south to Holland, northern Germany, and 
Hungary, although it has not yet been detected in Denmark 
(Winge, Danmarks Pattedyr, 78). \t formerly lived in Britain, 
first appearing in the Clevedon Cave, Somersetshire (Middle 
Pleistocene), where it is accompanied only by d/. madez and 
C. nates. In the “middle terrace” horizons of Crayford and 
Erith, and Fisherton, its remains are common and associated 
with those of lemmings and a pouched marmot (C?¢ed¢us) in 
addition to those of C. zzvalzs. It is known also from many 
later pleistocene deposits, as Ightham, Forest of Dean Cave, 
Langwith Cave, Derbyshire, and ‘Dog Holes,” Lancashire ; 
in such horizons its remains are scarce and associated with 
those of JZ. anglicus, lemmings, Cztel/us and Pika, while C. 
nwvalis is absent. The late pleistocene bones appear to be 
identical with those from individuals living in Holland and 
Germany. According to Hinton (of. czt., 503), AZ. ratticeps 
reached this country with Chzonomys from France during the 
later part of the ‘middle terrace” stage. 
Microtus malei (Hinton, Proc. Geol. Assoc., xx., 48, 1907, 
first referred to Chzonomys and subsequently to J/icrotus, Proc. 
Geol. Assoc., xxi., 494) is a ‘species with (typically) a rather 
generalised dental pattern such as that which probably character- 
ised the ancestor of several species like J/. ratticeps and C. 
nivalis,” and the specimens from the Clevedon Cave upon 
which this species was originally based represent only its 
nivaloid variation. It is only known from the Middle 
Pleistocene of Britain, occurring in the Clevedon Cave, 
