SEXUAL SELECTION 



358 



for carrying food to the moul b. In the males of certain 

 fresh-water prawns (Palaemon) the right leg is actually 

 longer than the whole body.'" The great size of the one 

 leg with its chelae may aid the male in fighting with his 

 rivals; but this will not account for their inequality in the 



Flo. 5. — Anterior part of body of Calli; nassa (from Milne-EdwardB), showing the 

 unequal and differently constructed right- uid left-hand chelaa of the male, 



N.B.— The artist by mistake has reversed the diawin^, and made the left-hand 



chela the largest. 



Fio. 6.— Second leg of male Orchestia 

 Tucuratinga (from Fritz Mnller). 



Fig. 7.— Ditto of female. 



female on the opposite sides of the body. In Gelasimus, 

 according to a statement quoted by Milne-Edwards," the 

 male and the female live in the same burrow, and this 

 shows that they pair; the male closes the mouth of the 



'" See a paper by Mr. C, Spence Bate, with figures, in "Proe, Zo&l. Soc," 

 1868, p. 363 ; and on the nomenclature of the genua, ibid., p. 686. I am greatty 

 indebted to Mr. Spence Bate for nearly all the above statements vilh respect 

 to the chelse of the higher crustaceans, 



" "Hist, Nat, des Crust,," torn, ii,, 1837, p, 60,, 



