Chap. IX.] CRUSTACEANS. 325 



The mental powers of the Crustacea are probably 

 higher than might have been expected. Any one who 

 has tried to catch one of the shore-crabs, so numerous on 

 many tropical coasts, will have perceived how wary and 

 alert they are. There is a large crab (Birgus latro), found 

 on coral islands, which makes at the bottom of a deep 

 burrow a thick bed of the picked fibres of the cocoa-nut. 

 It feeds on the fallen fruit of this tree by tearing off" the 

 husk, fibre by fibre ; and it always begins at that end 

 where the three eye-like depressions are situated. It then 

 breaks through one of these eyes by hammering with its 

 heavy front pincers, and, turning round, extracts the al- 

 buminous core with its narrow posterior pincers. But these 

 actions are probably instinctive, so that they would be 

 performed as well by a young as by an old animal. The 

 following case, however, can hardly be so considered : A 

 trustworthy naturalist, Mr. Gardner, 9 while watching a 

 shore-crab (Gelasimus) making its burrow, threw some 

 shells toward the hole. One rolled in, and three other 

 shells remained within a few inches of the mouth. In 

 about five minutes the crab brought out the shell which 

 had fallen in, and carried it away to the distance of a 

 foot ; it then saw the three other shells lying near, and 

 evidently thinking that they might likewise roll in, carried 

 them to the spot where it had laid the first. It would, I 

 think, be d'fficujt to distinguish this act from one per- 

 formed by man by the aid of reason. 



With respect to color which so often differs in the 

 two sexes of animals belonging to the higher classes, Mr. 

 Spence Bate does not know of any well-marked instances 

 with our British crustaceans. In some cases, however, 

 the male and female differ somewhat in tint, but Mr. Bate 



9 'Travels in the Interior of Brazil,' 1846, p. 111. I have given, in 

 my ' Journal of Researches,' p. 463, an account of the hahits of the 

 Birgos. 



