The Descent of Man

tic ornament (b, Fig. 59). The upper part of the
ring consists of two or three separate portions;
and there is only a trace of the thickening of the
portion which forms the black mark above the
white shade. This white shade itself is not as
yet much concentrated; and beneath it the surface
is brighter coloured than in a perfect balland-socket
ocellus. Even in the most perfect
ocelli traces of the junction of three or four
elongated black marks, by which the ring has
been formed, may often be detected. The irregular
sub-triangular or narrow mark (d, Fig.
59), manifestly forms, by its contraction and
equalisation, the thickened portion of the ring
above the white shade on a perfect ball-andsocket
ocellus. The lower part of the ring is invariably
a little thicker than the other parts (Fig.
57), and this follows from the lower black mark
of the elliptic ornament (b, Fig. 59) having originally
been thicker than the upper mark (c).
Every step can be followed in the process of
confluence and modification; and the black ring