C60 THE DESCENT OF MAN 



a bird allied to Polyplectron — that is, witli tail-coverts, 

 capable of erection and expansion, ornamented with two 

 partially confluent ocelli, and long enough almost to con- 

 ceal the tail-feathers, the latter having already partially 

 lost their ocelli. The indentation of the central disk and 

 of the surrounding zones of the ocellus, in both species of 

 peacock, speaks plainly in favor of this view, and is other- 

 wise inexplicable. The males of Polyplectron 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, during 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 splen- 

 did of living birds. 



Argus Pheasant. — Another excellent case for investiga- 

 tion is offered by the ocelli on the wing-feathers of the 

 Argus pheasant, which are shaded in so wonderful a man- 

 ner as to resemble balls lying loose within sockets, and con- 

 sequently 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 orna- 

 ments 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 Eaphael'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 in- 

 tended at first to draw the human figure. In order to dis- 

 cover how the ocelli have been developed, we cannot look to 

 a long line of progenitors, nor to many closely- allied forms, for 

 such do not now exist. But fortunately the several feathers 

 on the wing sufiice to give us a clew 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. 



