The Descent of Man

THE YOUNG MAY HAVE AN INTERMEDIA-
TE CHARACTER; OR, AGAIN, THEY MAY
DIFFER GREATLY FROM THE ADULTS IN
BOTH THEIR SEASONAL PLUMAGES.
The cases in this class are singularly complex;
nor is this surprising, as they depend on inheritance,
limited in a greater or less degree in
three different ways, namely, by sex, age, and
the season of the year. In some cases the individuals
of the same species pass through at
least five distinct states of plumage. With the
species, in which the male differs from the female
during the summer season alone, or,
which is rarer, during both seasons (41. For
illustrative cases, see vol. iv. of Macgillivray's
'History of British Birds;' on Tringa, etc., pp.
229, 271; on the Machetes, p. 172; on the Charadrius
hiaticula, p. 118; on the Charadrius pluvialis,
p. 94.), the young generally resemble the
females,—as with the so-called goldfinch of
North America, and apparently with the splendid
Maluri of Australia. (42. For the goldfinch