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THE AMERICAN NATURALIST [Vol. XLVIII 



Microtus orcadensis Millais 1904. South Orkney Islands. Belated to M. 

 sarnius of Guernsey and the Pleistocene M. corneri of South England. 

 Distinguished by its large size and dark color. 



Microtus sandayensis (Millais 1905). Sanday Island, N. Orkney group. 

 Allied to orcadensis, but skull differing; upper parts much lighter. 



Microtus sandayensis westrce Miller 1908. Westray Island, N. Orkney group. 

 Not so pale as in typical form; teeth differing a little. 



Arvicola amphibius (L. 1758). Typical subspecies. England and South 

 Scotland. Large; color moderately dark. 



Arvicola amphibius ater (Macgillivray 1832) —reta Miller 1910. Scot- 

 land, except southward. Darker, melanism frequent. The name was 

 changed on account of Hypudce-us terrestris var. ater Billberg 1827, but 

 the change is perhaps needless, as Billberg 's animal was not a sub- 

 species, and has not been treated as a species or subspecies under 



Apodemus hebridensis (de Winton 1895). Lewis and Barra islands, Hebri- 

 des. Large, with small ears; color dark. 



Apodemus hirtensis (Barrett-Hamilton 1899). Island of St. Kilda. Near 

 hebridensis, but skull larger and color darker. 



Apodemus fridariensis (Kinnear 1906). Fair Isle, Shetland group. Large; 



Apodemus fiavicollis wintoni (Barrett-Hamilton 1900). England. Under 



parts with duller color, pectoral spot more diffuse. 

 Mus muralis Barrett-Hamilton 1899. Island of St. Kilda. Like M. musculus 



Mus fceroensis (Clarke 1904). Faroe Islands. Larger than musculus and 



muralis; hind foot very robust; tail thickened. 

 Sciurus vulgaris leucourus Kerr 1792. Great Britain and Ireland. Small; 



tail drab, fading in summer to cream buff. No dark phase. 



Cervus claphus scoticus Lonnberg 1906. Great Britain. Color darker and 



less gray than in the related Norwegian form. 

 Capreolus capreolus thotti Lonnberg 1910. Great Britain. Darker, face 



darker than body. 



I thought it of interest to compare the above British list with 

 a similar one for the Spanish peninsula (Spain and Portugal). 

 The latter area is continuous northward with France, but the 

 Pyrenees constitute a barrier. The Iberian peninsula differs so 

 much in its recent geological history from Britain, and is at the 

 same time so much more southern, that we should expect to find 

 the faunal elements very different. This expectation is realized, 

 yet the difference in numbers between the two lists is not very 

 great, and the number of Iberian forms treated as distinct 

 species is exactly the same (12) as that for the British Islands. 

 This suprising result is evidently due to the numerous small 



