forms, for such do not now exist. But fortunately the several feathers
on the wing suffice to give us a clue to the problem, and they prove to
demonstration that a gradation is at least possible from a mere spot to
a finished ball-and-socket ocellus.
[Fig. 57. Part of secondary wing-feather of Argus pheasant, shewing two
perfect ocelli, a and b. A, B, C, D, etc., are dark stripes running
obliquely down, each to an ocellus. [Much of the web on both sides,
especially to the left of the shaft, has been cut off.]
Fig.59. Portion of one of the secondary wing-feathers near to the body,
shewing the so-called elliptic ornaments. The right-hand figure is
given merely as a diagram for the sake of the letters of reference. A,
B, C, D, etc. Rows of spots running down to and forming the elliptic
ornaments. b. Lowest spot or mark in row B. c. The next succeeding spot
or mark in the same row. d. Apparently a broken prolongation of the
spot c. in the same row B.]
The wing-feathers, bearing the ocelli, are covered with dark stripes
(Fig. 57) or with rows of dark spots (Fig. 59), each stripe or row of
spots running obliquely down the outer side of the shaft to one of the
ocelli. The spots are generally elongated in a line transverse to the
row in which they stand. They often become confluent either in the line
of the row and then they form a longitudinal stripe or transversely,
that is, with the spots in the adjoining rows, and then they form
transverse stripes. A spot sometimes breaks up into smaller spots,
which still stand in their proper places.
It will be convenient first to describe a perfect ball-and-socket
ocellus. This consists of an intensely black circular ring, surrounding
a space shaded so as exactly to resemble a ball. The figure here given
has been admirably drawn by Mr. Ford and well engraved, but a woodcut
cannot exhibit the exquisite shading of the original. The ring is
almost always slightly broken or interrupted (Fig. 57) at a point in
the upper half, a little to the right of and above the white shade on
the enclosed ball; it is also sometimes broken towards the base on the
right hand. These little breaks have an important meaning. The ring is
always much thickened, with the edges ill-defined towards the left-hand
upper corner, the feather being held erect, in the position in which it
is here drawn. Beneath this thickened part there is on the surface of
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