MARINE BIOLOGICAL STATION AT PORT ERIN. 113 



frequently found to have their shells covered by a dense 

 growth of small sea-weeds, zoophytes, and sponges, which 

 to some extent conceal the crab from observation when 

 it is in a rock pool or on the sea-shore at low tide. These 

 sea- weeds are found to be attached to little hooked spines, 

 and observations have shown that the crab attaches the 



Fig. XIX., Brachyura (Natural size). 



sea-weeds to them itself, apparently with a view to its 

 own disguise. We have generally some specimens of the 

 spider-crab, Hyas araneus, showing this concealment in 

 the tanks at Port Erin. Some other kinds of crabs are 

 so shaped and coloured as to be very like the stones and 

 other objects amongst which they live. Some again 



