Chap. IX.] 



CRUSTACEANS. 



321 



on the opposito sides of the body, and by the inequality be- 

 ing much greater in the male than in the female ; and why, 



Fig. 4.— Anterior part of bodv of Callianassa (from Milne-Edwards), showing 

 the unequal and differently-constructed right and left-hand chelae of the male. 



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

 hand chela the largest. 



Fig. 5. 



Fig. 6. 



Fig. 5.— Second leg of male Orchestia Tucuratinga (from Fritz Muller). 

 Fig. 6— Ditto of female. 



when they are of equal size, both are often much larger 

 in the male than in the female, is not known. The ehela3 

 are sometimes of such length and size that they cannot 

 possibly be used, as I hear from Mr. Spence Bate, for car- 

 rying food to the mouth. In the males of certain fresh- 

 water prawns (Paltemon) the right leg is actually longer 



