. The descent of man, and selection in relation to sex. Evolution (Biology); Sexual selection in animals; Sexual dimorphism (Animals); Sex differences; Human beings. 320 SEXUAL SELECTION. [Part II. from the left-hand one, the latter resembling in its sim- ple tapering joints the antenna; of the female. In the male the modified antenna is cither n swollen in the middle or angu- larly bent, or converted (fig. 3) into an elegant, and sometimes â wonderfully complex, prehensile organ.'^ It serves, as I hear from Sir J. Lubbock, to hold the fe- male, and for this same purpose one of the two posteri
. The descent of man, and selection in relation to sex. Evolution (Biology); Sexual selection in animals; Sexual dimorphism (Animals); Sex differences; Human beings. 320 SEXUAL SELECTION. [Part II. from the left-hand one, the latter resembling in its sim- ple tapering joints the antenna; of the female. In the male the modified antenna is cither n swollen in the middle or angu- larly bent, or converted (fig. 3) into an elegant, and sometimes â wonderfully complex, prehensile organ.'^ 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 chelffi on the opposite sides of the body are of unequal size, the right- hand one being, as I am informed by Mr. D. Spence Bate, generally, though not invariably, the largest. This inequality is often much greater in the male than in the female. The two chcloD also often diflfer in structure (figs. 4 and 6), the sriialler one resembling those of the fe- male. What advantage is gained by their inequality in size. Fig. 3.âLabirlocera Darwinii (from Lubbock). a. Part of ric^ht-hand anterior nnteniia of male, forming a prelionsilc organ. b. Postorior pair of the thoracic logs of male. c. Ditto of female. 5 Sec Sir J. Lubbock in 'Annals, and Mas- of Nat. Hirt.' vol. xi. 1853, pis. i. and x.; and vol. xii. (18o3) pi. vii. Sec also Lubbock in ' Transact. Ent. Soc' vol. iv. new series, 1856-1858, p. 8. With respect to the zig- zagged antcnnjc mentioned below, sec Fritz Miiller, ' Facts and Argu- ments for Darwin,' 1850, p. 40, Please note that these images are extracted from scanned page images that may have been digitally enha
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Keywords: ., bookcentury1800, bookdecade1870, booksubj, booksubjecthumanbeings
