THE SKOMER BANK MOUSE 421 



In 1898 I became aware of the existence of the Skomer Bank Mouse. 

 In October of that year Marsden sent me two taken by Mills, to which 

 Mills afterwards added ten more. These remained in my collection 

 until the publication in 1900 of Miller's "Preliminary Revision of the 

 European Red-backed Mice" (JProc. Wash. Acad. Sci., 26th July 1900, 

 83-109). This suggested a re-examination of the Skomer specimens, 

 with the result that in 1906 I described the new British Mammal 

 and definitely assigned it a place amongst other related forms of 

 neighbouring countries. It is clear that to Drane belongs the honour 

 of discovering this species (see Proger, Field, 20th Feb. 1904, 321 ; 

 Thomas, Field, 12th March 1904, 451), but, that, without Miller's paper, 

 Drane's discovery was meaningless and its value could not be recognised. 



Status : — E. skomerensis belongs to a group of European bank mice, 

 characterised by size larger than that of glareolus, and distributed in 

 isolated colonies, on mountains or islands. These are comparable to 

 the two continental forms of Lepus timidus, and may logically be treated 

 as sub-species of one central form, E. nageri (Schinz, 1845). The 

 meaning of this group is shown by Hinton's determination of a closely 

 allied form or forms from the late Pleistocene of Ightham, Kent ; Brix- 

 ham, Devonshire; and St Lawrence, Isle of Wight. This palaeontological 

 evidence and the characters of skomerensis indicate that the latter 

 is a somewhat modified survivor from an older fauna, which has 

 been everywhere driven out by the newer and more recent arrival, 

 glareolus; the remains of this last occur for the first time in Britain 

 in the Pleistocene of Ightham, alongside those of the then existing 

 member of the older group. The reality of the group is not invali- 

 dated by the fact that one of its forms, E. nageri, intergrades with 

 E. glareolus through the sub-species E. n. helveticus. The large and 

 small forms still remain distinct in origin. As in the case of Lepus, 

 isolated members of the group have become so far differentiated as 

 to have attained specific rank ; and indeed it is only a matter of 

 convenience whether such geographically isolated forms as norvegicus 

 and nageri be given the superior or the inferior grade. The following 

 are the known forms, excluding E. alstoni and E. erica of Scotland, 

 described below :— 



E. nageri noi-vegicus (Miller) of western Norway, and north at least 

 to Nordland, has a broad mantle not sharply defined from the buffy- 

 grey flanks, the hind foot 184 to 19, a heavily built skull, the condylo- 

 basal length of which is 24-2 to 26-2 mm., and m^ has usually three 

 internal infolds. E. n. vasconice (Miller), of the French side of the 

 Pyrenees, is very similar to the last, but perhaps larger, and with a 

 duller, narrower mantle and less buffy sides. E. n. nageri (Schinz) 

 of the Alps and the northern Italian mountains, is slightly larger than 

 F-- n. norvegicus (hind foot, i8-8 to 20; condylo-basal length of skull, 



