Identifier: descentofmansele01darw (find matches)
Title: The descent of man, and selection in relation to sex
Year: 1871 (1870s)
Authors: Darwin, Charles, 1809-1882
Subjects: Evolution Natural selection Heredity Human beings -- Origin Evolution
Publisher: London, J. Murray
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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ber of the smelling-threads,whilst other individuals varied in the shape and size of Chap. IX. CRUSTACEANS. 329 their chelae ; so that of the former, those which were bestable to find the female, and of the latter, those which werebest able to hold her when found,have left the greater number ofprogeny to inherit their respec-tive advantages.4 In some of the lower crusta-ceans, the right-hand anteriorantenna of the male differsgreatly in structure from theleft-hand one, the latter re-sembling in its simple taperingjoints the antennae of the fe-male. In the male the modi-fied antenna is either swollenin the middle or angularly bent,or converted (fig. 3) into anelegant, and sometimes wonder-fully complex, prehensile organ.5It serves, as I hear from Sir J.Lubbock, to hold the female,and for this same purpose oneof the two posterior legs (b) onthe same side of the body isconverted into a forceps. Inanother family the inferior orposterior antennae are curiously zigzagged: in themales alone.
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Fig. 3. Labidocera Darwinii (fromLubbock). Part of right-hand anterior an-tenna of male, forming a pre-hensile organ. Posterior pair of thoracic legs ofmale. Ditto of female. 4 Facts and Arguments for Darwin, English translat. 1869, p. 20.See the previous discussion on the olfactory threads. Sars has de-scribed a somewhat analogous case (as quoted in Nature, 1870,p. 455) in a Norwegian crustacean, the Pontoporeia affinis. 5 See Sir J. Lubbock in Annals, and Mag. of Nat. Hist. vol. si.1853, pi. i. and x.; and vol. xii. (185H) pi. vii. See also Lubbock in Transact. Ent. Soc vol. iv. new series, 1856-1858, p. 8. With respectto the zigzagged antenna? mentioned below, see Fritz Miiller, Factsand Arguments for Darwin 1869, p. 40, foot-note. 330 SEXUAL SELECTION. Part II. In the higher crustaceans the anterior legs form apair of chelae or pincers, and these are generallylarger in the male than in the female. In many speciesthe chelae on the opposite sides of the body are ofunequal size, tbe

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