THE COMMON WREN OP THE SHETLAND ISLANDS. 295 



form occurs which is as conspicuously barred as the Faroese and 

 Shetland race, and which is intermediate between them in size, 

 whilst it scarcely differs from the Algerian and Turkestan race 

 in colour, and may fairly be regarded as subspecifically distinct 

 under the name of Troglodytes parvulus hirtensis. 



The typical form of the Common Wren varies in length of 

 wing from 1*7 to 2*0 inches. Out of ten examples two measure 

 1*85, whilst four are larger and four are smaller, so that the 

 mean between the two extremes appears to represent a fair 

 average. The length of tail varies from 1*1 to 1*37 inches, the 

 average of the ten examples being 1*22. The length of the 

 culmen varies from *45 to "56 inches, the average of the ten 

 examples being *515. The length of the hallux, without the 

 claw, varies from '34 to *40, the average being -37. 



The range of variation appears to be as nearly as possible 

 ten per cent, from the mean in each direction ; the mean being, 

 wing 1*85, tail 1*22, culmen *51, and hallux '37. Although the 

 number of examples that have been measured from the Shetland 

 Islands, St. Kilda, and the Faroe Islands is scarcely sufficient to 

 establish an average, there can be little doubt that the average 

 size of these three races is greater than that of the typical race ; 

 and there is no doubt whatever that the maximum dimensions 

 exceed those of the typical race. 



Four examples of the Shetland Island race of the Common 

 Wren vary in length of wing from 1*81 to 1*96, in length of tail 

 from 1*11 to 1*22, in length of culmen from '56 to *6, and in 

 length of hallux, without the claw, from '4 to '43 ; the mean 

 being, wing 1*91, tail 1*18, culmen *58, hallux *41. 



Three examples of the Faroese race of the Common Wren 

 vary in length of wing from 1*95 to 2*15, in length of tail from 

 1*86 to 1*5, in length of culmen from *58 to *62, and in length of 

 hallux, without the claw, from *41 to '43. 



It thus appears that whilst the Shetland form of the Common 

 Wren is on an average a larger bird than the typical form, but is 

 not quite so large on an average as the Faroese form, it never- 

 theless intergrades with both, so that none of the European 

 forms can claim more than subspecific rank on the ground of size. 



The typical form of the Common Wren also varies consider- 

 ably in the robustness of its feet. They are generally very 

 slender, but occasionally examples are found in which they are 



