3;6 MURID^ 



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 Mus 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 Arvicola; his Microtus 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 Mammals of Western 

 Europe (191 2) there are eight genera, Muscardinus, Evotomys, 

 Microtus, Arvicola, Apodemus { = Mus sylvaticus), Micromys 

 ( = Mus minutus), Epimys ( = Mus rattus and M. norvegicus), 

 and Mus, 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 



