62 



The Study of Animal Life 



their stolen shells, especially if these be covered by the 

 Hydroid Hydractinia or other organisms. Various other 

 crabs (Stenorkynchus, Inachus, Maia, Dromia, Pisa) are 

 masked by the seaweeds, sponges, and zoophytes which 

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

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

 Plymouth that the crabs sometimes fix the seaweeds for 



Fig. 12. — Sack-bearing caterpillar (Sacco^hora). (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 



