Chap. IX. 
CRUSTACEANS. 
329 
their chelae ; 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 when found, a 
have left the greater number of 
progeny to inherit their respec- 
tive advantages. 4 
In some of the lower crusta- 
ceans, the right-hand anterior 
antenna of the male differs 
greatly in structure from the 
left-hand one, the latter re- 
sembling in its simple tapering 
joints the antennae of the fe- 
male. In the male the modi- 
fied antenna is either swollen 
in the middle or angularly bent, 
or converted (fig. 3) into an 
elegant, and sometimes wonder- 
fully complex, prehensile organ. 5 
It serves, as I hear from Sir J. 
Lubbock, to hold the female, 
and for this same purpose one 
of the two posterior legs ( h ) on 
the same side of the body is 
converted into a forceps. In 
another family the inferior or 
posterior antennae are “ curiously zigzagged 
males alone. 
Fig. 3. Labidocera Darwinii, (from 
Lubbock). 
a. Part of right-hand anterior an- 
tenna of male, forming a pre- 
hensile organ. 
Z>. Posterior pair of thoracic legs of 
male. 
c. Ditto of female. 
m 
the 
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. xi. 
1853, pi. 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 zigzagged antennae mentioned below, see Fritz Muller, ‘ Facts 
and Arguments for Darwin ’ 1869, p. 40, foot-note. 
