Crustacea. 



6577 



they imagine the danger has passed away, and then, cautiously 

 resuming their natural position, they steal slowly away to the nearest 

 place of security. 



The edible crab, when it has put on this trick, cannot be awakened 

 out of it by any amount of annoyance. But the swimming crab, if 

 touched, will soon throw off the cheat and run away, raising high and 

 opening wide the two great biting-claws, and hasten to a place 

 of safety, where once arrived it will bury itself in the soil beneath and 

 permit only its dark back to appear on a level with the surface, that it 

 may be overlooked, in its general resemblance to the half-buried 

 stones upon the beach. But it is not asleep, no, nor like the foolish 

 ostrich think that if it denies itself the power to see, that therefore it 

 is safe ; the eyes are raised and watchfully keep guard. In the com- 

 mon shrimps upon our shores this process of hiding is very prettily 

 performed. In the little pools among the stones, where the shore is 

 sandy, if you surprise a small shoal of these Crustacea, they spring 

 with a simple flap of the tail to a considerable distance, where, resting 

 upon the sand at the bottom of the pool, they gently disturb it with 

 their feet and by their own gravity sink into the hollow ; but when 

 they have buried themselves to the level of the surface, they keep the 

 sand upon their backs by the aid of the long filamentary extremities 

 of the lower antennae. These brush up, in small quantities at a time, 

 the particles of sand ; and when the labour is complete, I question if 

 the sharpest eye could detect the spots where they lie concealed, 

 unless they were seen to hide, and the black shining eyes and the 

 antennae alone be exposed. And there they lie at peace, secure in 

 their concealment, let the danger continue ever so long. The slight 

 jerking movement of the inner and the waving motion of the outer 

 are all that tells of animal life beneath ; and, since these are organs of 

 hearing and smell, we may fairly infer that with the eyes they assist 

 to watch and intimate when danger is near and the animal may 

 securely come from its retreat. 



But some are not so satisfied, and will not rest until they are con- 

 siderably beneath the sand. This is the case with Portumnus 

 variegatus, a pretty little shield-back mottled species of crab. Timid 

 to excess, it almost lives beneath the sand, but this may arise partly 

 from the circumstance of its habitat being between the tides, so that 

 when the water has receded it buries itself to find moisture. At 

 , Swansea, where I have found them in considerable numbers, I had to 

 dig for them with a trowel, but it was not difficult to find their resting- 

 XVII. 2 m 



