. The descent of man, and selection in relation to sex. Evolution; Natural selection; Sexual selection in animals; Human beings -- Origin; Sexual dimorphism (Animals). "and obviously for the same ; In male dragon-flies, " the appendages at the tip of the tail are modified in an almost infinite variety of curious patterns to enable them to embrace the neck of the female-" Lastly, in the males of many in- sects, the legs are furnished with peculiar spines, knobs, or spurs; or the whole leg is bowed or thickened, but this is by no means invariably a sexual character; or on
. The descent of man, and selection in relation to sex. Evolution; Natural selection; Sexual selection in animals; Human beings -- Origin; Sexual dimorphism (Animals). "and obviously for the same ; In male dragon-flies, " the appendages at the tip of the tail are modified in an almost infinite variety of curious patterns to enable them to embrace the neck of the female-" Lastly, in the males of many in- sects, the legs are furnished with peculiar spines, knobs, or spurs; or the whole leg is bowed or thickened, but this is by no means invariably a sexual character; or one pair, or all three pairs are elongated, sometimes to an extravagant In all the orders, the sexes of many species present differences, of which' the meaning is not understood. One curious case is that of a beetle (fig. 9), the male of which has the left mandible much enlarged; so that the mouth is greatly distorted. In another Carabidous beetle, the Eurygna- thus,9 we have the unique case, as far as known to Mr. Wollaston, of the head of the female being much broader and larger, though in a variable degree, than that of the male. Any number of such cases could be given. They abound in the Lepidoptera: one of the most extraordinary is that cer- tain male butterflies have their fore-legs Fig 9 _ Taphro- more or less atrophied, with the tibise and deres distortus tarsi reduced to mere rudimentary knobs. (much enlarged). J Upper figure, The win^s, also, in the two sexes often differ male; lower fig- & > > ure, female. jn neuration,10 and sometimes considerably about Pcnthe, and others in inverted commas, are taken from Mr. Walsh, 1 Practical Entomologist,' Philadelphia, vol. ii. p. 88. 8 Kirby and Spence, ' Introduct.' etc., vol. iii. pp. 332-336. 9 'Insecta Maderensia,' 1854, p. 20. 10 E. Doubleday, «Annals and Mag. of Nat. Hist.' vol. i. 1848, p. Please note that these images are extracted from scanned page images that may have been digitally enhanced f
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Keywords: ., boo, bookcentury1800, bookdecade1870, booksubjectnaturalselection
