The Descent of Man

spring; but these tints, as Mr. Sclater states, "do
not last long, disappearing generally in about
six weeks or two months after they have been
attained." Certain finches shed the margins of
their feathers in the spring, and then become
brighter coloured, while other finches undergo
no such change. Thus the Fringilla tristis of the
United States (as well as many other American
species) exhibits its bright colours only when
the winter is past, whilst our goldfinch, which
exactly represents this bird in habits, and our
siskin, which represents it still more closely in
structure, undergo no such annual change. But
a difference of this kind in the plumage of
allied species is not surprising, for with the
common linnet, which belongs to the same family,
the crimson forehead and breast are displayed
only during the summer in England,
whilst in Madeira these colours are retained
throughout the year. (84. On the pelican, see
Sclater, in 'Proc. Zool. Soc.' 1868, p. 265. On the
American finches, see Audubon, 'Ornithologi-