THE ORKNEY GRASS MOUSE 45; 



the group became extinct through unsuccessful competition 

 with M. agrestis neglectus, just as the latter succumbed in the 

 southern and lowland districts before the advance of M. hirtus. 

 The persistence of M. sarnius in an island far to the south 

 shows that these mice owe their survival to freedom from 

 competition in islands rather than to any other factor ; else- 

 where they have probably succumbed to such competition, 

 helped by the attacks of carnivora, from which large palatable 

 mice inhabiting shallow burrows can only escape in the presence 

 of moderately deep snow. 



THE ORKNEY GRASS MOUSE. 



MICROTUS ORCADENSIS, Millais. 



1805. Mus AGRESTIS (species), George Barry, History of the Orkney Islands, ed. i., 

 314; ed. ii., 320, 1808 (part); Low, Fauna Orcadensis, 1813, 25 (part); T. E. 

 Buckley, Trans. Nat. Hist. Soc, Glasgow, i., 49, 1883-86 (part). 



Local names and terminology : — Cuttick or puttick (Millais) ; vole- 

 mouse oiV)Z.xxy, 1805 (see under History), a name which seems to have 

 been the source of the term "vole," as already discussed above on 

 pp. 398 and 443 (see also Edmonston's Etymological Glossary of the 

 Shetland and Orkney Dialect, 1 866). 



Distribution : — This mouse is confined to the Orkneys, where it is 

 known from all the bigger islands except, perhaps, the rocky Hoy ^ ; 

 it is abundant in parts of South Ronaldshay, Pomona, Shapinshay, 

 Rousay, Westray, and Sanday. 



History: — This mouse was first mentioned by Barry, minister of 

 Shapinshay, in 1805 : — "The Short-tailed Field Mouse {^Mus agrestis, 

 Lin. Syst), which with us has the name of the vole mouse, is very often 

 found in marshy grounds that are covered with moss and short heath, 

 in which it makes roads or tracks of about 3 inches in breadth, and 

 sometimes miles in length, much worn by continual treading, and 

 warped into a thousand different directions" (in ed. ii., 1808; ed. i. not 

 seen). 



Subsequently, to Barry's time the mouse appears to have been 

 known to many naturalists, none of whom examined it critically. 

 Baikie and Heddle appear to have confounded it with the Water 

 Rat, other writers with M. agrestis. In August 1886 Millais's attention 

 was attracted by some individuals which he observed in Pomona, but 



' Note that Baikie and Heddle {Addendum, 97) record the capture of two 

 specimens of Mus amphibius in the burn by Rackwick, in Hoy, by M. F. Heddle in 

 September 1844. 



VOL. n. 2 G 



