428 THE DESCENT OF MAN. 



As far, then, as gradation throws light on the steps by which 

 the magnificent train of the peacock has been acquired, hardly 

 anything more is needed. If we picture to ourselves a progeni- 

 tor of the peacock in an almost exactly intermediate condition 

 between the existing peacock, with his enormously elongated tail- 

 coverts, ornamented with single ocelli, and an ordinary gallina- 

 ceous bird with short tail-coverts, merely spotted with some color, 

 we shall see a bird allied to Polyplectron — that is, with tail- 

 coverts, capable of erection and expansion, ornamented with two 

 partially confluent ocelli, and long enough almost to conceal the 

 tail-feathers, the latter having already partially lost their ocelli. 

 The indentation of the central disc and of the surrounding zones 

 of the ocellus, in both species of peacock, speaks plainly in favor 

 of this view, and is other ;7ise inexplicable. The males of Poly- 

 plectron are no doubt beautiful birds, but their beauty, when 

 viewed from a little distance, cannot be compared with that of 

 the peacock. Many female progenitors of the peacock must, dur- 

 ing a long line of descent, have appreciated this superiority; for 

 they have unconsciously, by the continued preference of the most 

 beautiful males, rendered the peacock the most splendid of living 

 birds. 



Argus Pheasant. — Another excellent case for investigation Is 

 offered by the ocelli on the wing-feathers of the Argus pheasant, 

 which are shaded in so wonderful a manner as to resemble balls 

 lying loose within sockets, and consequently differ from ordinary 

 ocelli. No one, I presume, will attribute the shading, which has 

 excited the admiration of many experienced artists, to chance 

 — to the fortuitous concourse of atoms of coloring matter. That 

 these ornaments should have been formed through the selection 

 of many successive variations, not one of which was originally 

 intended to produce the ball-and-socket effect, seems as incredible, 

 as that one of Raphael's Madonnas should have been formed by 

 the selection of chance daubs of paint made by a long succession 

 of young artists, not one of whom intended at first to draw the 

 human figure. In order to discover how the ocelli have been de- 

 veloped, we cannot look to a long line of progenitors, nor to 

 many closely-allied forms, for such do not now exist. But fortu- 

 nately the several feathers on the wing sufilce 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. 



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 



