566 TBE DESCENT OF MAN 



gated 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 

 equalization, the thickened portion of the ring above the 

 white shade on a perfect ball-and-socket ocellus. The lower 

 part of the ring is invariably a little thicker than the other 

 parts (see Fig. 57), and this follows from the lower black 

 mark of the elliptic ornament (6, Fig. 59) having originally 

 been thicker than the upper mark (c). Every step can be 

 followed in the process of confluence and modification; 

 &nd the black ring which surrounds the ball of the ocellus 

 is unquestionably formed by the union and modification 

 of the three black marks, b, c, d, of the elliptic ornament. 

 The irregular zig-zag black marks between the successive 

 ocelli (see again Fig. 57) are plainly due to the breaking 

 up of the somewhat more regular but similar marks between 

 the elliptic ornaments. 



The successive steps in the shading of the ball-and-socket 

 ocelli can be followed out with equal clearness. The brown, 

 orange and pale leaden narrow zones, which border the lower 

 black mark of the elliptic ornament, can be seen gradually to 

 become more and more softened and shaded into each other, 

 with the upper lighter part toward the left-hand corner ren- 

 dered still lighter, so as to become almost white, and at the 

 same time more contracted. But even in the most perfect 

 ball-and-socket ocelli a slight difference in the tints, though 

 not in the shading, between the upper and lower parts of 

 the ball can be perceived, as before noticed; and the line 

 of separation is oblique, in the same direction as the bright- 

 colored shades of the elliptic ornaments. Thus almost every 

 minute detail in the shape and coloring of the ball-and-socket 

 ocelli can be shown to follow from gradual changes in the 

 elliptic ornaments; and the development of the latter can 

 be traced by equally small steps from the union of two al- 

 most simple spots, the lower one (Fig. 58) having some dull 

 fulvous shading on its upper side. 



The extremities of the longer secondary feathers, which 



