FREE MESSMATES. 23 



We should perhaps speak here of an association of 

 another kind, the nature of which it is difficult to ascer- 

 certain ; I refer to the little crab, the Turtle Crab of 

 Brown, which is met with in the open sea on the cara- 

 pace of turtles, and sometimes on sea-weeds. It may be 

 supposed that it takes advantage of the carapace of its 

 neighbour, in order to transport itself at little expense 

 into different latitudes, and it is asserted that the sight 

 of this crustacean gave confidence to Christopher Colum- 

 bus, eighteen days before the discovery of the New 

 World. Besides this animal, a whole society chooses 

 this movable habitation : in addition to the cirrhipedes 

 we also find the Tanais, which is not, however, con- 

 demned to live there always. 



The macrourous decapods are more rarely found as 

 messmates, but still a Palffimon is sometimes seen on 

 the body of an Actinia, according to Semper, and another 

 in the branchial cavity of a Pagurus. But that which 

 is more generally known, is the presence in the Euplec- 

 tella aspergillum of the palsemon which lodges in this 

 fairy palace. It is probable that the Euplectella of the 

 Atlantic, recently observed near the Cape Verd Islands 

 by the naturalists on board the Challenger, also conceals 

 this crustacean in its interior. We may also allude here 

 to the Hypoconcha tabulosa, a crab whose carapace is too 

 soft to allow it to venture out undefended, and which 

 covers itself with the shell of a bivalve mollusc. 



Among the various associations of this kind, none is 

 more remarkable than that, of the soldier-crabs, so abun- 

 dant on our coasts, and called by the names of Bernard the 

 Hermit and Kakerlot by the Ostend fishermen. It is 

 well known that these crabs are decapod crustaceans, 



