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DARWIN, CHARLES. Secondary sexual characters of Insects.

(Chapters x. & xi. pp. 341-423, of the author's 'Descent of Man.' London: 1871.)

In discussing the argument of sexual selection, the author, after referring, amongst other instances, to the diversified structures possessed by the males of the Insecta for seizing the females, the differences between sexes of which the meaning is not understood, and especially the difference in size between the sexes, and briefly referring to sexual distinctions, &c. in the Thysanura, Diptera, Heteropterous and Homopterous Hemiptera (especially the musical powers possessed by the males alone in the latter suborder), enters at some length upon the pugnacity, colours, and structurally much-diversified musical instruments of the males of the Orthoptera, the colour-differences in the Neuroptera, the pugnacity and colours of the Hymenoptera, the colours, pugnacity, and horny developments of the males, and the possession of stridulating organs by both sexes of the Coleoptera, and the various well-known sexual mo-

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difications of the Lepidoptera. Observations on the proportional numbers of the sexes in the Insecta occur at p. 309 et seq. Many woodcuts of various sexual developments in the different orders are given, and are mostly original; and the author's usual accuracy and earnest endeavour to get at truth, independently of theory, are as conspicuous in this collateral branch of this argument as in his more pretentious works.