94 ON THE VARIATION OF SPECIES. 



confined in its range to the Amazons valley, whilst S. Vesta 

 extends beyond this region over Guiana and the central 

 valleys of the Andes ; it seems, therefore, to have acquired a 

 power of adaptation to a much wider diversity of local con- 

 ditions. Insects seem to be well adapted to furnish data in 

 illustration of this interesting but difficult subject. This 

 arises chiefly from the ease with which ample suites of speci- 

 mens can be obtained for comparison from many points in 

 the areas of distribution both of species and varieties. It is 

 scarcely necessary to add that the conclusions thus arrived at 

 will apply to all organic beings. 



