2 jo The Descent of Man. Pakt II. 



Mr. Bate adds, " if they fought, the victory was a bloodless one, 

 " for I saw no wounds." This same naturalist separated a male 

 sand-skipper (so common on our sea-shores), Gammarus marinus, 

 from its female, both of whom were imprisoned in the same 

 vessel with many individuals of the same species. The female, 

 when thus divorced, soon joined the others. After a time the 

 male was put again into the same vessel ; and he then, after 

 Bwimming about for a time, dashed into the crowd, and without 

 any fighting at once took away his wife. This fact shews that 

 in the Amphipoda, an order low in the scale, the males and 

 females recognise each other, and are mutually attached. 



The mental powers of the Crustacea are probably higher than 

 at first sight appears probable. Any one who tries to catch one 

 of the shore-crabs, so common on tropical coasts, will perceive 

 how wary and alert they are. There is a large crab (Bir</tis 

 lutro), found on coral islands, which makes a thick bed of the 

 picked fibres of the cocoa-nut, at the bottom of a deep burrow. 

 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 albuminous core with its narrow 

 posterior pincers. But these actions are probably instinctive, so 

 that they would be performed as well by a young animal as by 

 an old one. The following case, however, can hardly be so con- 

 sidered : a trustworthy naturalist, Mr. Gardner, 14 whilst watching 

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

 towards 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 difficult to distinguish this act from one 

 performed by man by the aid of reason. 



Mr. Bate does not know of any well-marked case of difference 

 of colour in the two sexes of our British crustaceans, in which 

 respect the sexes of the higher animals so often differ. In some 

 cases, however, the males and females differ slightly in tint, but 

 Mr. Bate thinks not more than may be accounted for by their 

 different habits of life, such as by the male wandering more 

 about, and being thus more exposed to the light. Dr. Power 



14 'Travels in the Intel :or of 463, an account of the habits of the 

 Brazil,' 184-6, p. 111. I have given, Birgus. 

 in my ' Journal oi Researches,' p. 



