ARTHROI'ODA 



>;i 



extended the animal may measure four or five meters acn 

 Sponges ate often found attached to the carapaee of sum.' rubs, 

 and undoubtedly serve to conceal them from their enemies, 



FlG. 104. Variouscrabs. (After Bell and de Haan.from Parker and Haswell's Text-book.) 



while the sponge has the advantage of being carried about to 

 fresh feeding grounds. The borrowed houses of the hermit crabs 



