318 Proceedings of the Royal Irkli Academy. 



The Skomer Voles thus exceed those of Great Eritain generally 

 by an average of 18 mm. on the body leng-th, so that they are neaidy a 

 quarter as large again, and these proportions are borne out ia the 

 average dimensions of the tail, hindfoot, ear, and skull. There is, 

 besides, a difference in the proportionate lengths of the tail vertebrae 

 to the total length of the two forms, that of the ordinary British 

 being about as 31-50, that of the Skomer Voles as 33 per cent, of the 

 total length. 



I was much surprised to find that the Skomer Vole is clearly allied 

 to the forms inhabiting Boreal Europe. It is quite closely related to 

 JEvotomys norvegicus Miller, of ^Norway, E. nageri (Schinz) of the Alps, 

 and JE. vasconice Miller of the Pyrenees. 



In a recent paper Mr. Grerrit S. Miller, junior,^ has, excluding the 

 Arctic JE.rutilus (Pallas) and the very distinct^ .S". rufocanus (Sundevall) 

 of [N'orthern Europe, divided the Bank Voles of Continental Europe 

 into two sets. One of these, consisting of the three species mentioned 

 in the last paragraph, is characteristic of the mountains, and cor- 

 responds in its distribution with the Variable Hares. The other 

 includes a number of smaller lowland forms, amongst which is the 

 British, the E. hercynicus ^ hritannicus of Miller. 



The Skomer Vole constitutes a foui'th member of the Boreal group, 

 which, like its allies, is totally distinct from the Voles of the surround- 

 ing country. I regret that I have very few specimens of the other 

 Boreal forms wherewith to compare it. It is, however, less grey 

 than E. nageri, of which Mr. Oldfield Thomas has shown me several 

 specimens obtained by himself near Locarno in Italian Switzerland, 

 while it appears to have a shorter tail than E. norvegicus. Further, 

 on comparison with the dimensions given iu Mr. Miller's tables, it 

 seems to be the smallest Boreal foirm yet described, 



I do not propose to attempt an explanation of the occurrence of 

 this colony of Voles almost indistinguishable from those of Boreal 

 Europe, nor why they appear to be confined to a small, wind-swept 

 island. It is, for the present, sufficient to place the facts on record, 

 noting, however, that the Skomer Vole is in no sense of the word a 

 stunted representative of its genus such as might reasonably be 



1 "Preliminary Eevision of the European Eed-backed Mice." Proceedings of 

 the "Washington Academy of Science, vol. xi., pp. 83 to 109, July 26, 1900. 



- A form ■which Mr. Miller has, I think, somewhat unnecessarily raised to sub- 

 generic rank. 



•' I do not, however, accept the validity of Mr. Miller's arguments for the 

 abolition of the well-known term glareolus and the substitution for it of hercynicus. 



