68 ANNALS OF SCOTTISH NATURAL HISTORY 



the mice of the above-mentioned islands. These two points, 

 I think, show that the Fair Isle mice are varying along a 

 different line from either hebridensis or hirtensis. 



I have not been able to examine a very satisfactory 

 series of Field-mice from Orkney and Shetland, but the 

 average measurements show that the mice of these islands 



o 



have a slightly larger hind-foot and ear than in M. s. inter- 

 inedius from the mainland, and probably these differences 

 would be more noticeable in a larger series. 



In neither of these Archipelagos are the mice so rich in 

 colour, especially on the flanks, as in the specimens from 

 Fair Isle. 



Taking into consideration these differences, I think the 

 Fair Isle mice are quite entitled to be ranked as a sub- 

 species, and therefore I propose the name of 



MUS SYLVATICUS FRIDARIENSIS, 1 sub-spec, nov. 



Type, a male in the Royal Scottish Museum. 



Distinguishing Characteristics. A large, well-developed 

 M. s. intennedius, resembling in size and proportions M. s. 

 wintoni, except in the case of the ear, which is smaller. In 

 coloration rather richer than M. s. intennedius, especially on 

 the flanks, and with a distinct line of demarcation between 

 the upper and under sides. 



Skull, a large edition of M. s. intermedius, from 28 to 

 28.5 mm. in length. 



For comparison I give the measurements of the various 

 British sub-species. 



H. and B. Tail. Hind-foot. Ear. 



.]/. s. intermedius* (62 ^s) . . 92.6 88.2 22.6 15.4 



M. s. celticus* (2 ^ sand 4 9 s ) 85.3 80.8 22.3 14.6 



M. s. hebridensis^ (3 ^s and i 9 ) IO ^ 97-5 2 4-25 I 5-75 



M. s. hirtensis^ (5 g s and 5 9 s) . 104 100 24.7 16.25 



M. s. ^v^lltoni' i (i and 3 $s) . 110.75 m-75 2 3-75 J S 



J/. s. fridariensis (4 ^s and 2 $ s) 109 108 23.58 16. 6 



In conclusion I have to thank Captain Barrett-Hamilton 

 for help in working out this sub-species. 



1 Fair Isle is the Fridarey of the Orkneyinga Saga. This name was suggested 

 to me by Mr. Eagle Clarke. 



2 "P.Z.S." r'goo, pp. 423-425. 



3 "Ann. Scot. Nat. Hist." 1906, p. 3. 



