MARINE ARTHROPODS 281 



Attempt to pull one from its hold, or even take other than the 

 gentlest means to arrest its progress, and you will probably find 

 that it suddenly parts company with one of its broad claws in its 

 endeavour to escape ; and, unless some special precautions be 

 taken to remove these crabs, it is possible that quite half the 

 specimens taken will have been damaged in this way during their 

 struggles to escape. If, however, you gently thrust the point of a 

 penknife beneath the body, and then apply the thumb above, you 

 may lift them from a stone without injury. Another plan is to 

 press a frond of smooth sea weed as closely as possible to the 

 surface of the stone in the front of the crabs, and then allow them 

 to crawl on to it, or cause them to do so if necessary. The piece 

 of weed, with crab or crabs attached, may then be bagged for future 

 examination. 



On turning over the Broad-clawed Crab its under surface will 

 be seen to be perfectly smooth, with an appearance closely re- 

 sembling that of white porcelain. Its foot-jaws, also, are propor- 

 tionately large, and closely fringed with hairs ; and the last pair of 

 legs, which are very slender in build, are folded closely beneath 

 the body. Further, the abdomen is wide, composed of six distinct 

 movable segments, and terminating in a tail-fin composed of five 

 fringed plates. 



Drop the crab into water, and it will immediately extend its 

 abdomen, which it will flap sharply under its body somewhat after 

 the manner of lobsters and shrimps, and thus swim backward by a 

 series of jerks as it sinks to the bottom. On reaching the bottom 

 it instantly grasps the solid material, applies itself closely to the 

 surface, and glides away into the nearest chink it can find. 



As one observes the nature and movements of these interesting 

 little crabs one cannot fail to see how beautifully their form and 

 structure are adapted to their habits. They are peculiarly con- 

 structed for abode in narrow chinks and crannies, and for feeding on 

 the small forms of life that inhabit such sheltered places. Their 

 legs move in the plane of their flattened bodies, and as they glide 

 among the confervse and other low forms of life that encrust the 

 stones of the beach they feel their way by, and are possibly also 

 guided by the sense of smell located in, their long outer antennae, 

 while the close fringes of their claws and foot-jaws form admirable 

 sweep-nets by means of which the little animals that form their 

 food are swept towards the mouth. 



We have other species of stone crabs, one or two of which 



