162 THE STORY OF LIFE IN THE SEAS. 



sea-weeds, escape the attention of their enemies 

 and hide for safety among the plants they simu- 

 late. Sometimes, however, the weeds will grow 

 upon the shells of the animals, and thus hide 

 them even more effectually. One of the most 

 remarkable instances occurs in a Spider-crab that 

 is common upon our own coasts. The Inaclms, as 

 it is called, is usually covered with a little forest 

 of algse, which do not grow there naturally, but 

 are actually placed on the carapace by the Crab 

 itself. If the plants be scraped off artificially the 

 Crab will go in search of fresh ones, carefully 

 chew the bases until they are soft, and then 

 deliberately decorate the carapace with them as 

 before. 



There are some Molluscs that artificially decor- 

 ate themselves with little shells and other objects 

 in such a manner as to completely hide their 

 general form. One of the most remarkable 

 instances of this occurs in the Gastropod Xeno- 

 phora, which covers its own shell with numbers 

 of others belonging to a smaller species, so that 

 in the natural state it has the appearance of a 

 conglomerate of shells. The manner in which the 

 smaller shells are fixed has not yet been described, 

 but from the orderly arrangement which they 

 exhibit in some cases there can be little doubt 

 that they are deliberately placed in position by 

 the Gastropod itself and not attached by acci- 

 dental contact. 



In both these cases it is clear that the reason 

 for the phenomena described is that of affording 

 a covering or mantle, which hides or obscures the 

 real form and character of the living animals. 



