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Show 138 SEXUAL SELECTION :- BIRDS. PART Jf. the spring the males, as previously described, strut about before the comparatively plain-coloured females, expanding and erecting their tail and w~ng-feathers, which are ornamented with numerous ocelh. I request the reader to turn back to the drawing (fig. 51, p. 90) of a Polyplectron. In P. Napoleonis the ocelli are confined to the tail, and the back is of a rich metallic blue, in which respects this species approaches the Java peacock. P. Hardwickii possesses a peculiar top-knot, somewhat like that of this same ldnc1 of peacock. The ocelli on tho wings and tail of the several species of Polyplectron are either circular or oval, and consist of a beautiful, iridescent, greenishblue or greenish-purple disc, with a black border. This bo1;der in P. chinquis shades into brown which is edged with cream-colour, so that the ocellus is here surrounded with differently, though not brightly, shaded concentric zones. The unusual length of the tail-coverts is another highly remarkable character in Polyplectron; for in some of the species they are half as long, and in others two-thirds of the length of the true tail-feathers. The tail-coverts are ocellated, as in the peacock. Thus the several species. of Polyplectron manifestly make a graduated approach in the length of their tail-coverts, in the zoning of the ocelli, and in some other characters, to the peacock. Notwithstanding this approach, the first species of Polyplectron which I happened to examine almost made me give up the search; for I found not only that the true tail-feathers, which in the peacock are quite plain, were ornamented with ocelli, but that the ocelli on all the feathers differed fundamentally from those of the peacock, in there being two on the same feather, (fig. 54),. one on each side of the shaft. Hence I CIIAl'. xrv. GRADATION OF CIIARACTEllS. 139 concluded that tho early 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 ncar each other ; that in tho tail-feathers of P. Ilardwickii they touched each other; and, finally, that in the taU-coverts ofthi ·same species as well as of P. malaccense (fig. 55) they were actually confluent. As tho central part alone is confluent, an indentation is left at both the upper and lower ends ; and the surroundin!r coloured Fig. 54, Part of n tall-covert of Poly- '-' plcctron chinquis, with the two ocelli zones arc likewise indented. or nat. eizc. A single ocellus is thus formed on each tail-covert, though still plainly betraying its double origin. These confluent ocelli differ from the single ocelli of the peacock in having an indentation at both ends, instead of at the lower or basal end alone. Tho explanation, however, of this difference is not difficult; in some species of Polyplectron l'lg. 55. Purt of a lllil-covcrt of Polythe two oval ocelli on the plectron mulncccnsc, with the two ocelli, partially confluent, of llllt. size. same feather stand parallel to each other ; in other species (as in P. chinquis) they converge towards one end ; now the partial confluence of two convergent ocelli would manifestly leave a much. |