148 . SEXUAL SELECTION : BIRDS. PAPa" II. 



the other parts (see fig. 56), and this follows from the 

 lower black mark of the elliptic ornament (h) having 

 been originally thicker than the upper mark (c). Every 

 step can be followed in the process of confluence and 

 modification ; and the black ring which surrounds the ball 

 of the ocellus is unquestionably formed by the union 

 and modification of the three black marks, h, c, d, of the 

 elliptic ornament. The irregular zigzag black marks 

 between the successive ocelli (see again fig. 56) are 

 plainly due to the breaking up of the somewhat more 

 regular but similar marks between the elliptic orna- 

 ments. 



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

 socket ocelli can be followed out w^ith 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 

 towards the left-hand corner rendered still lighter, so as 

 to become almost white. But e\en 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 was before espe- 

 cially noticed), the line of separation being oblique, 

 in the same direction with the brioht coloured shades 

 of the elliptic ornaments. Thus almost every minute 

 detail in the shape and colouring of the ball-and-socket 

 ocelli can be shewn 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 almost simple spots, the lower one (fig. 57) 

 having some dull fulvous shading on the upper side. 



The extremities of the longer secondary feathers 

 which bear the perfect ball-and-socket ocelli are pecu- 

 larly ornamented. (Fig. 59.) The oblique longitudinal 



