Archive image from page 285 of The descent of man, and. The descent of man, and selection in relation to sex descentofmanse00darw Year: 1870 284 THE DESCENT OF MAN: [PART IL each other. In the one form the male is furnished with more numerous smelling-threads, and in the other form with more powerful and more elongated chelae, or pincers, which serve to hold the female. Fritz Miiller suggests that these differences between the two male forms of the same species may have originated in certain individuals having varied in the number of the smelling-threads, while other individuals varied in the
Archive image from page 285 of The descent of man, and. The descent of man, and selection in relation to sex descentofmanse00darw Year: 1870 284 THE DESCENT OF MAN: [PART IL each other. In the one form the male is furnished with more numerous smelling-threads, and in the other form with more powerful and more elongated chelae, or pincers, which serve to hold the female. Fritz Miiller suggests that these differences between the two male forms of the same species may have originated in certain individuals having varied in the number of the smelling-threads, while other individuals varied in the shape and size of their che'lae ; so that of the former, those which were best able to find the female, and of the latter, those which were best able to hold her, have left the greatest number oi progeny to inherit their respective advantages. In some of the lower crustaceans, the right anterior antenna a of the male differs greatly in structure from the left, the latter resembling in its simple tapering joints the antennae of the female. In the male the modi- fied antenna is either swollen in the middle or angularly bent, or con- verted (fig. 4) into an elegant, and sometimes wonderfully complex, pre- hensile It serves, as I hear from Sir J. Lubbock, to hold the female, and for this same purpose one of the two posterior legs {F) on the same side of the body is converted into a forceps. In another family the inferior or posterior antennae are curiously zigzagged' in the males alone. In the higher crustaceans the an> terior legs are developed into chelae, or pincers; and these are generally larger in the male than in the female -so much so that the market value of Fig. 4.—Labidocera Darwinii (from Lubbock), a. Part of right anterior antenna of male form- the male ediblc crab (Caucer paurus), ing a prehensile organ, b. Pos- r~ c -rd /' terior pair of thoracic legs of male. aCCOrdmg tO Mr. C. Spcnce BatC, IS c. Ditto of female. - fQma\e. In many species th
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