| OCR Text |
Show 1.4.6 SEXUAL SELECTION: BIRDS. Pa:Jt'l' li. loped and more brightly coloured. To ~he right ~nd above this spot (b), with its bright s~admg, there IS a long, narrow, black mark (c), belongmg to the same row and which is archecl a little downwards so as to. fac~ (b). It is also narrowly edged ou the lowe~· sidewith a fulvous tint. To the left of and above c, m the- A II C cl }qg, 58. Portion of one of the Secondary wing-feath ers nenr to the body ; shewing the so-cnllcd elliptic ornaments. 'l'be right-hand figure is given merely as a. dingrum for the salce of the letters of reference. A, B. C, &c. Rows of spots running down I c. The next succeeding spot or mark in to nml iorming tbe elliptic omu- the same row. mcnts. d • .A.pparently a. broken prolongation of b. J"owest spot or mark In row B. the 8pot c in the same row .l:l. same oblique direction, but always more or less distinct from it, there is another black mark (d). This mark isgenerally sub-triangular and irregular in shape,. but h11 the one lettered in the diagram is unusually narrow,. elongated, and regular. It apparently consists of a lateral and broken prolongation 0f the mark (c), as I CHAP. Xl\". GRADATION OF CHARACTEHS. 147 infer from traces of similar prolongations from the succeeding upper spots; but I do not feel sure of this. These three marks, b, c, and d, with the intervening bright shades, form together the so-called elliptic ornament. These ornaments stand in a line parallel to the shaft, and manifestly conespond in position with the ball-and-socket ocelli. Their extremely elegant appearance cannot be appreciated in the drawing, as the orange and leaden tints, contrasting so well with the black marks, cannot be shewn. Between one of the elliptic ornaments and a perfect ball-and-socket ocellus, the gradation is so perfect that it is scarcely possible to decide when the latter term ought to be used. I regret that I have not given an additional drawing, besides fig. 58, which stands about half:.way in the series between one of the simple spots and a perfect ocellus. The passage from the elliptic ornament into an ocellus is effected by the elongation and greater curvature in opposed directions of the lower black mark (b), and more especially of the upper one (c), together with the contraction of the irregular subtriangular or narrow mark (d), so that at last these three marks become confluent, forming an irregular elliptic ring. This ring is gradually rendered more and more circular and regular, at the same time increasing in diameter. Traces of the junction of all three elongated spots or marks, especially of the two upper ones, can still be obseryed in many of the most perfect ocelli. The broken state of the black ring on the upper side of the ocellus in fig. 56 was pointed out. The inegular sub-triangular or narrow mark (d) manifestly forms, by its contraction and equalisation, the thickened portion of the ring on the left upper side of the perfect ball-and-socket ocellus. The lower part of the ring is invariably a little thicker than L 2 |
