The Descent of Man

chelae of the male. N.B.—The artist by mistake
has reversed the drawing, and made the lefthand
chela the largest.
Fig. 6. Second leg of male Orchestia Tucuratinga
(from Fritz Muller).
Fig. 7. Ditto of female.]
In the higher crustaceans the anterior 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 the
male edible crab (Cancer pagurus), according
to Mr. C. Spence Bate, is five times as great as
that of the female. In many species the chelae
are of unequal size on the opposite side of the
body, the right-hand one being, as I am informed
by Mr. Bate, generally, though not invariably,
the largest. This inequality is also often
much greater in the male than in the female.
The two chelae of the male often differ in structure
(Figs. 5, 6, and 7), the smaller one resem-