48 THE HAUNTS OF LIFE 



carapace of a rock-lobster, the unbreakable 

 shells of molluscs, the scales of fishes often 

 sharp and formidable, and so on up to the 

 complicated encasement of the edible turtle. 



MASKING 



The " walking wood of Birnam " was an 

 episode in Scottish history, immortalised in 

 Shakespeare's Macbeth, where a band of soldiers 

 camouflaged themselves by cutting down 

 branches of trees and carrying these with 

 them as they stealthily advanced. So some 

 crabs on the seashore fix seaweeds on the back 

 of the shell and mask themselves effectively. 

 They can steal upon their victims ; they can 

 efface themselves in the eyes of their enemies. 

 Sometimes the cloak consists of zoophytes, or 

 pieces of sponge, or half of the tunic of a sea- 

 squirt ; but oftenest it is a cloak of seaweed. 

 1 1 is as if the crab carried a garden on its back. 

 The camouflaging is often shown by the sand- 

 crab (Hyas araneus) and by the narrow-beaked 

 crab (S tenor hynchus longirostris) ; but it is seen 

 in many others. The disguising seems very 

 deliberate on the crab's part, and if the disguise 

 is picked off, the crab often sets about clothing 



