Note 44 — Chapter VI

Mr. Gould, however, holds that the difference of coloration is due to the different degrees of exposure to the sun's rays, the brilliantly-colored species being inhabitants of the edges of the forest. Birds from Ucayali, in the centre of the continent, are far more splendid than those which represent them in countries nearer the sea, owing to the clearer atmosphere inland. But it is a fact, at least exceptional to this theory, that the "Cock of the Rock" (Rupicola) on the western side of the Andes (Esmeraldas) is of a richer, deeper color than the same species on the eastern slope (Napo). In keeping with Mr. Gould's theory is the statement by Mr. Bates, that the most gaudy butterflies (the males) flutter in the sunshine.