48 THE HAUNTS OF LIFE 



nate carapace of a rock-lobster, the unbreak- 

 able 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 sol- 

 diers 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. Some- 

 times 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. It 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 

 (Stenorhynchus longlrostrls] ; but it is seen in 

 many others. The disguising seems very de- 

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

 is picked off, the crab often sets about clothing 



