302 



THE DESCENT OF MAN, 



water prawns (Palaemon) the right leg is actually longer than 

 the whole body.* The great size of the one leg witli its 

 chelse may aid Vue male in fighting with his rivals; but this 



Fig. 5. Anterior part of body of Callianassa (from Milne-Edwards), 

 showing the unequal and differently-constructed riglr and 

 left hand chelae or the male. 



N. B. The artist by mistake has reversed the drawing, and made the 

 left-hand chela the largest. 



Fig. 6. Fig. 7. 



Second leg of male Orchestia Tucuratinga (from Fritz Muller). 



Fig. 6. ^_. .. 



Fig. 7. Ditto of female 



will not account for their inequality in the female on the 

 opposite sides of the body. In Gelasimus, according to a 



*See a paper by Mr. C. Spence Bate, with figures in " Proc. 

 Zoolog. Soc," 1868, p. 363; and on the nomenclature of the genus, 

 ibid, p. 585. I am greatly indebted to Mr. Spence Bate for nearly all 

 the above statements with respect to the chelje of the higher 

 crustaceans, 



