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Show 340 SEXUAL SELECTION. PAr:T 1'1. can I find any well-marked instances of sexual differences such as more particularly concern us. I:n Glomeris limbata, however, and perhaps in some few other species, the males differ slightly in colour ~rom the females; but this Glomeris is a highly variable species. In the males of the Diplopoda, the legs belonging to one of the anterior segments of the body, or to the posterior segment, are modified into prehensile hooks which serve to secure the female. In some species of Iulus the tarsi of the male are furnished with membranous suckers for the same purpose. It is a much more unusual circumstance, as we shall see when we treat of Insects, that it is the female in Lithobius which is furnished with prehensile appen<. lages at the extremity of the body for holding the male. 17 17 Walckenaer et P. Gervais, 'Hist. Nat. des Insectes: Aptcrcs, .. tom. iv. 1847, p. 17, lD, GS. C HAP. :X. SEXUAL SELECTION. 341 CHAPTER X. SECO::SDARY SEXUAL CHARACTER::> OF INSECTS. Diversified structures possessed by the males for seizing the females -Differences between the sexes, of which the meaning is not understood- Difference in size between the sexes- 'l'hysanura - Diptera- Hemiptera- Homoptera, musical powers possessed by the males alone - Orthoptera, musical instt·uments of the males, much diversified in structure; pugnacity; coloursNeuroptera, sexual differences in colour-Hymenoptera, pugnacity and colours- Coleoptera, colours ; furnished with great horns, apparently as an ornament ; battles; stridulating organs generally common to both sexes. IN the immense class of insects the sexes sometimes differ in their organs for locomotion, and often in their sense-organs, as in the pectinated and beautifully plumose antennre of the males of many species. In one of the Ephemerre, namely Ohloeon, the male has great pillared eyes, of which the female is entirely destitute.1 'fhe ocelli are absent in the females of certain other insects, as in the J.Vlutillidre, which are likewise destitute of wings. But we are chiefly concerned with structures by which one male is enabled to conquer another, either in battle or courtship, through his strength, pugnacity, ornaments, or music. The innumerable contrivances, therefore, by which the male is able to seize the female, may be briefly passed over. Besides the complex structures at the apex of the abdomen, which ought perhaps to be ranked as primary 1 Sir J. Lubbock, 'Transact. Linnean Soc.' vol. xxv. 1866, p. 484. With respect to the Mutillidre see Westwood, ' Modern Class. oflnsects,' vol. ii. p. 213. |
