. The descent of man, and selection in relation to sex. Evolution (Biology); Sexual selection in animals; Sexual dimorphism (Animals); Sex differences; Human beings -- Origin. 320 SEXUAL SELECTION. [Part II. a from the left-hand one, the latter resembling in its sim- ple tapering joints the antennae of the female. In the male the modified antenna is either swollen in the middle or angu- larly bent, or converted (fig. 3) into an elegant, and sometimes wonderfully complex, prehensile It serves, as I hear from Sir J. Lubbock, to hold the fe- male, and for this same purpose one of the two
. The descent of man, and selection in relation to sex. Evolution (Biology); Sexual selection in animals; Sexual dimorphism (Animals); Sex differences; Human beings -- Origin. 320 SEXUAL SELECTION. [Part II. a from the left-hand one, the latter resembling in its sim- ple tapering joints the antennae of the female. In the male the modified antenna is either swollen in the middle or angu- larly bent, or converted (fig. 3) into an elegant, and sometimes wonderfully complex, prehensile It serves, as I hear from Sir J. Lubbock, to hold the fe- male, and for this same purpose one of the two posterior legs (b) on the same side of the body is converted into a forceps. In an- other family the inferior or pos- terior antenna? are "curiously zig- zagged " in the males alone. In the higher crustaceans the anterior legs form a pair of chelae or pincers, and these are gener- ally larger in the male than in the female. In many species the Fig. 3.—Labirtocera Darwinii chelae On the Opposite sides of the (from Lubbock). l l . a. Part of ns?ht-band anterior body are of unequal Size, the right- antenna of male, forming a l-i i • T ~~» :^-T^„*^^^ prehensile oro-an hand one being, as I am mlormea *' P£o?SerSfthethoraciC by Mr. D. Spence Bate, generally, c. Ditto of female. though not invariably, the largest. This inequality is often much greater in the male than in the female. The two chelae also often differ in structure (figs. 4, 5 and 6), the smaller one resembling those of the fe- male. What advantage is gained by their inequality in size 5 See Sir J. Lubbock in 'Annals, and Mag. of Nat. Hist.' vol. xi. 1853, pis. i. and x.; and vol. xii. (1853) pi. vii. See also Lubbock in • Transact. Ent, Soc' vol. iv. new series, 1856-1858, p. 8. With respect to the zig- zagged antennae mentioned below, see Fritz Miiller, ' Facts and Argu- ments for Darwin,' 1869, p. 40, Please note that these images are extracted from scanned page images that may have been
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectevoluti, bookyear1872
