376 MURIDA& 
' 
and Water ‘“Voles.” No further change was made until in 
1835 Jenyns, by the addition of the ‘“ Bank Campagnol,” 
brought the list up to nine. Fleming’s arrangement of genera 
also continued unaltered through the works of MacGillivray 
(1837) and Bell (1837 and 1874), until in 1895 Lydekker 
replaced Myoxus by Muscardinus and Arvicola by Microtus ; 
he also admitted the Yellow-necked Mouse, bringing the number 
of species up to ten. Johnston (1903) adopted the genus 
Evotomys for the ‘Bank Vole”; he graded the Yellow- 
necked Mouse as one of five sub-species of his JZus sylvaticus, 
which, if all reckoned, make a total of thirteen. At this period 
the institution of sub-species and the preliminary difficulties of 
arranging them caused some instability. Millais (1905), re- 
taining the same genera as Johnston, placed the Water Rat 
in the sub-genus Avrvzcola; his Mzcrotus orcadensis raised 
the number of species to ten, in addition to which five sub- 
species of Field Mouse, two of House Mouse, three of Black 
Rat, with the Skomer and Sanday ‘Voles,” both as sub- 
species, made a total of nineteen recognisable forms. No more 
recent work of authority has been published on _ British 
mammals, but in Miller’s Catalogue of the Mammats of Western 
Europe (1912) there are eight genera, Muscardinus, Evotomys, 
Microtus, Arvicola, Apodemus (= Mus sylvaticus), Micromys 
(= Mus minutus), Epimys (= Mus rattus and M. norvegicus), 
and JZus, the latter now restricted to the House Mouse and its 
allies. Almost all the old species have now become genera, 
and, with the various recently discovered insular forms, they now 
reach nineteen, or, adding sub-species and admitting the Alex- 
andrine Rat, a total of twenty-four recognisable forms. Some 
of the recent additions to the list are as distinct as any of the 
older forms, and are of considerable importance as representing 
survivals from an older fauna, and there can be no doubt about 
the interest of all of them. The present work in the main 
follows Miller’s arrangement, but more recent study and ampler 
material has suggested alterations and one or two additions. 
Pelage:—The general colour is derived from a mixture of 
the tips of at least two kinds of hairs. Of these the sparse 
longer are dusky; they represent the bristles of some foreign 
species. The abundant shorter hairs form the underfur; they 
