. The descent of man, and selection in relation to sex. Evolution (Biology); Sexual selection in animals; Sexual dimorphism (Animals); Sex differences; Human beings. Chap. XIV.] GRADATION OF CHARACTERS. 133. progenitors of the peacock could not have resembled in any degree a Polyplectron. But on continuing my search, I observed that in some of the species the two ocelli stood very near each other ; that in the tail-feathers of P. liard- wickii they touched each other; and, finally, that in the tail-coverts of this same spe- cies as well as of P. malaccense (Fig, 55) they were actually confluen
. The descent of man, and selection in relation to sex. Evolution (Biology); Sexual selection in animals; Sexual dimorphism (Animals); Sex differences; Human beings. Chap. XIV.] GRADATION OF CHARACTERS. 133. progenitors of the peacock could not have resembled in any degree a Polyplectron. But on continuing my search, I observed that in some of the species the two ocelli stood very near each other ; that in the tail-feathers of P. liard- wickii they touched each other; and, finally, that in the tail-coverts of this same spe- cies as well as of P. malaccense (Fig, 55) they were actually confluent. As the central part alone is confluent, an indenta- tion is left at both the ui^per and lower ends; and the sur- rounding colored zones are likewise indented. A single ocellus is thus formed on each Fi«- of a taii-covert of Poly plectron ehinquis, with tail-covert, though still plainly betraying its double origin. These confluent ocelli difler from the single ocelli of the peacock in having an indenta- tion at both ends, instead of at the lower or basal end alone. The explanation, however, of this difierence is not diflacult; in some species of Polyplec- ti'on the two oval ocelli on the same feather stand parallel to each other; in other species (as in P. chinquis) they con- Ym. 55. -Part of a tuii-coveit of verge toward one end; now Polyplectron malaccense, with ° ' the two ocelli, partially conflu- the partial confluence of two ent, of natural size. the two ocelli of natural Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Darwin, Charles, 1809-1882. New York, D. Appleton and company
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