CRUSTACEANS. 305 



males of a Brazilian Gelasimus, a species furnished with 

 immense pincers, were placed together in a glass vessel by 

 Fritz Miiller, they mutilated and killed one another. Mr. 

 Bate put a large male Caret fins mcenas into a pan of 

 water, inhabited by a female which was paired with a 

 smaller male; but the latter was soon dispossessed. 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), Gam- 

 marus 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 veseel; and he then, after swimming about 

 for a time, dashed into the crowd, and without any fighting 

 at once took away his wife. This fact shows that in the 

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

 females recognize 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 {Birgus latro), found on coral islands, which makes a 

 thick bed of the picked fibers of the cocoanut, at the 

 bottom of a deep burrow. It feeds on the fallen fruit of 

 this tree by tearing off the husk, fiber by fiber; and it 

 always begins at that end where the three eye-like depres- 

 sions are situated. It then breaks through one of these 

 eyes by hammering with its heavy front pincers, and, turn- 

 ing round, extracts the albuminous core with its narrow 

 posterior pincers. But these actions are probably instinct- 

 ive, 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 considered: a trustworthy naturalist, Mr. 

 Gardner,* 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 a dis- 



*" Travels in the Interior of Brazil." 1846, p. 111. I have given in 

 my "Journal of Researches," p. 463, an account of the habits of the 

 Birgus. 



