124 HABITS AND INSTINCTS OP ANIMALS. CHAP. IV* 



swimming and leaping, in the latter of which they are 

 very expert. But the most remarkable circumstance in 

 the motions of both these animals is that by which, at 

 stated periods, they change their shells, or, in case of 

 accident, cast off their injured claws, which are quickly 

 replaced with fresh ones. Before the latter operation 

 is effected, the animal, it is said, appears to suffer pain ; 

 it then moves its claw, for some time, from side to 

 side, holding it afterwards perfectly steady, when it will 

 suddenly give a gentle crack and drop off, not, as it 

 has been stated, at the joint, but in the smoothest part 

 of the limb.* 



(148.) There is a peculiarity of motion in certain 

 apterous insects, which is without parallel in any other 

 class of animals ; we allude to the constant practice of 

 the great majority of crabs, and of a few of the spiders, 

 of always walking sideways, instead of with their head 

 towards the point to which they are proceeding. This 

 they do, not slowly, as one would expect from their 

 thick body and heavy claws, but sometimes with 

 amazing rapidity. We well remember the amusement 

 we derived, when in Brazil, from running after a par- 

 ticular species of crab, one of whose claws was almost 

 as big as its whole body : they lived in little holes in 

 the sand, and, at the ebb of the tide, would come out 

 by dozens to seek their food from among the wreck 

 which had been left : yet they were so wary, that, 

 although they would venture more than fifteen, or even 

 twenty, yards from their burrow, we never succeeded in 

 catching one. They shuffled off sideways towards their 

 hole the moment they espied us, holding up their gi- 

 gantic claw, at the same time, as if it was of no weight. 

 Thus intimidated from seizing the creature, and not 

 wishing to deprive it of life, even had we the power 

 (which, from its agility, was very questionable), every 

 one of them got safe to its hole, before we succeeded in 

 intercepting its retreat. 



* Anim. Biog. vol. iii. p. 381. 



