The Descent of Man and Selection in Relation to Sex, Vol. II (1st Edition)Darwin, Charles
Science
The Descent of Man and Selection in Relation to Sex, Vol. II (1st Edition)
Darwin, Charles
Evolution (Biology); Human beings -- Origin; Sex differences; Sexual dimorphism (Animals); Sexual selection in animals
I will next describe the other extreme of the series, namely the first
trace of an ocellus. The short secondary wing-feather (fig. 57), nearest
to the body, is marked like the other feathers, with oblique,
longitudinal, rather irregular, rows of spots. The lowest spot, or that
nearest the shaft, in the five lower rows (excluding the basal row) is a
little larger than the other spots in the same row, and a little more
elongated in a transverse direction. It differs also from the other
spots by being bordered on its upper side with some dull fulvous
shading. But this spot is not in any way more remarkable than those on
the plumage of many birds, and might easily be quite overlooked. The
next higher spot in each row does not differ at all from the upper ones
in the same row, although in the following series it becomes, as we
shall see, greatly modified. The larger spots occupy exactly the same
relative position on this feather as those occupied by the perfect
ocelli on the longer wing-feathers.
By looking to the next two or three succeeding secondary wing-feathers,
an absolutely insensible gradation can be traced from one of the
above-described lower spots, together with the next higher one in the
same row, to a curious ornament, which cannot be called an ocellus, and
which I will name, from the want of a better term, an “elliptic
ornament.” These are shewn in the accompanying figure (fig. 58). We here
see several oblique rows, A, B, C, D (see the lettered diagram), &c., of
dark spots of the usual character. Each row of spots runs down to and is
connected with one of the elliptic ornaments, in exactly the same manner
as each stripe in fig. 56 runs down to, and is connected with, one of
the ball-and-socket ocelli. Looking to any one row, for instance, B, the
lowest spot or mark (_b_) is thicker and considerably longer than the
upper spots, and has its left extremity pointed and curved upwards. This
black mark is abruptly bordered on its upper side by a rather broad
space of richly-shaded tints, beginning with a narrow brown zone, which
passes into orange, and this into a pale leaden tint, with the end
towards the shaft much paler. This mark corresponds in every respect
with the larger, shaded spot, described in the last paragraph (fig. 57),
but is more highly developed and more brightly coloured. To the right
and above this spot (_b_), with its bright shading, there is a long,
narrow, black mark (_c_), belonging to the same row, and which is arched
a little downwards so as to face (_b_). It is also narrowly edged on the
lower side with a fulvous tint. To the left of and above _c_, in the
same oblique direction, but always more or less distinct from it, there
is another black mark (_d_). This mark is generally sub-triangular and
irregular in shape, but in the one lettered in the diagram is unusually
narrow, elongated, and regular. It apparently consists of a lateral and
broken prolongation of the mark (_c_), as I infer from traces of
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