444 MURIDA—AGRESTIS 
History :—Although described by Bellamy in 1839, it cannot be - 
pretended that the status and affinities of this mouse have been made 
at all clear until quite recently. All the earlier descriptions, even when 
technically valid, must be regarded as due to misapprehensions, the 
earlier writers not having been acquainted with the true relationships 
of agrestzs and the continental arva/is. 
The exact distribution of this Grass Mouse is imperfectly known, 
but it certainly ranges from Wales to Austrian Galicia, ascending to 
4000 feet in Switzerland (Fatio). The common European form, which 
is found from the eastern shores of the English Channel and the Baltic 
at least to Central Germany and South-western France, is just dis- 
tinguishable as a sub-species, JZ. 4. dazllont (de Sélys), on account of 
its narrower skull. Another sub-species, J7. roztanus (Bocage) of 
Portugal and North-western Spain, which differs chiefly in its small 
auditory bulla, is graded as a sub-species of agvestzs by Miller, but may 
prove to be more nearly related to hzrtus. 
M. hirtus is the Grass Mouse of England, Wales, and the lowlands 
of Scotland, where it is common all over the country, including the 
islands of Wight and Anglesey, except in woods and on the higher 
hills. In the Highlands of Scotland and probably on the hills of the 
south, also in the Hebrides, it is replaced by one or other of the forms 
of AZ. agrest’s, and in the Orkneys by MW. orcadensis. It is absent from 
Ireland, the Isle of Man, Bardsey Island, and, as far as is known, from 
all other islands except those mentioned above. 
Distribution in time and Status:—This mouse is not known asa 
fossil in Britain, although remains of “voles” are numerous in late 
pleistocene deposits. It is therefore probably a quite recent post- 
pleistocene immigrant, which appears to have established itself in the 
more low-lying and southern parts of the country, at the expense of 
the older forms of the JZ. agrestzs type, in a manner paralleled by that 
of Lepus europeus and Evotomys glareolus. It appears to have arrived 
in Britain before the separation of Wight and Anglesey, but after that 
of all the other islands. 
Description :—The Common Grass Mouse is distinguishable in its 
genus by its comparatively small size (hind foot, 17 to 18, and condylo- 
basal length of skull not more than 24-6 to 26 mm.), small bull, and 
comparatively reddish upper side. 
The colour of the upper side is near “ tawny russet,” very indistinctly 
overlaid with black. The sides are paler and washed with buff; the 
under-side and feet are light ochraceous buff, through which colour the 
dusky basal portions of the hairs show here and there. The tail is 
bicoloured, above brown, beneath like the belly. 
The brightest individuals run very near Evotomys glareolus, but lack 
the clear light belly of the latter. 
