REPRESENTATIVE SPECIES. 85 



forcibly illustrated by certain species and races of 

 Palaearctic Owls. One very remarkable instance is 

 furnished by the Tawny_ Owl (Strix aluco). Its 

 range extends throughout the southern portion of 

 the Palaearctic region, from Scandinavia and North 

 Africa to China. Here again we find almost pre- 

 cisely the same modification of colour in obedience 

 to climate as in the Grouse, but in this case the 

 variation depends to a great extent on the rainfall 

 the gray examples from areas where the climate is 

 dry, the rich brown examples from areas of ex- 

 cessive moisture, and the intermediate examples 

 from regions of moderate climate. The Short- 

 eareoMDwl (Strix brachyotus), another wide-ranging 

 species subject to great difference of climate, 

 presents us with very similar facts. 



It is surprising that the most prominent sup- 

 porters of Darwin's theory of Natural Selection 

 should attempt to account for these differences in 

 colour presented by so many representative forms 

 by suggesting that they are due to protective 

 causes. It would be impossible to show how a 

 lighter or a darker shade of brown, so finely 

 gradated as to merge insensibly from one extreme 

 to another in a sufficiently large series of indi- 

 viduals, is of the slightest use to the form or race 



