62 The Study of Animal Life part \ 



their stolen shells, especially if these be covered by the 

 Hydroid Hydractinia or other organisms. Various other 

 crabs {Stenorhynchus, Inachus, Maia, Dromia, Pisa) are 

 masked by thfe seaweeds, sponges, and zoophytes which 

 cover their carapace. Moreover, the interest of this mask- 

 ing is increased by the fact observed by Mr. Bateson at 

 Plymouth that the crabs sometimes fix the seaweeds for 



Fig. 12. — Sack-bearing caterpillar (^Saccophora). (From Bates.) 



themselves. Mr. Bateson describes how the crab seizes a 

 piece of weed, tears off a piece, chews the end in his mouth, 

 and then rubs it firmly on his head and legs until it is 

 caught by the curved hairs and fixed. " The whole pro- 

 ceeding is most human and purposeful. Many substances, 

 as hydroids, sponges, Polyzoa, and weeds of many kinds 

 and colours, are thus used ; but these various substances 

 are nearly always symmetrically placed on corresponding 



