96 THE LIFE OF CRUSTACEA 



Crabs" (Dromiida), of which one species, Dromia 

 vulgaris (Plate IX.), occurs on the southern coasts 

 of Britain, have also the last two pairs of legs 

 elevated on the back and used in a similar way ; but 

 in this case the covering is usually a mass of living 

 sponge, one of the Sea-squirts (Tunicata), or some 

 similar organism. 



Even more remarkable are the " masking " habits 

 of the Spider Crabs (Oxyrhyncha). In these the 

 carapace is almost always covered with sea-weeds, 

 zoophytes, and other organisms which afford a very 

 effective disguise. For example, specimens of the 

 British species of Hyas (H. araneus and H. coarctatus) 

 and Maia (M. squinado Plate XIII.), which are very 

 common on our coasts, readily escape the notice of 

 the collector, as they lurk in the rock-pools. They 

 are slow-moving animals, and the carapace and 

 limbs are usually quite hidden by dense tufts of 

 growing sea-weed, sponges, and other organisms. 

 By observing the Crabs in an aquarium, it has been 

 found that they actually dress themselves, plucking 

 pieces of weed and the like and placing them on the 

 carapace, where they are held in position by numerous 

 hooked hairs. The transplanted fragments continue 

 to live and grow until the Crab appears like a minia- 

 ture moving forest. Still more strange is the fact 

 that the Crabs appear to be able in some degree to 

 adapt the nature of their covering to their surround- 

 ings. It has been found that specimens dressed in 



