Oh. XVn.] THE PILL-MAKING CEAB. 289 



peared no living thing to which they might be attributed. 

 I naturally supposed that the little crab inhabiting the hole 

 had ejected the sand in Httle balls in the construction of his 

 habitation ; but an approaching footstep was an immediate 

 signal for the disappearance of the little creatures. By 

 remaining quite quiet, however, on a patch 30 or 40 feet 

 square, which was covered with their holes, I was able to 

 watch their remarkable habits. On the first approach, a 

 peculiar twinkle on the sand was visible, which required a 

 quick eye to recognise as a simultaneous and rapid retreat 

 of all the little crabs into their holes, not a siagle one re- 

 maining visible. Kneeling down and remaining motionless 

 for a few minutes, I noticed a slight evanescent appearance, 

 like a flash or bursting bubble, which the eye could scarcely 

 follow. This was produced by one or more of the little 

 crabs coming to the surface, and instantly darting down 

 again, alarmed at my proximity. It was only by patiently 

 waiting, like a statue, that I could get them to come out 

 and set to work. They were of various sizes, the most 

 common being that of a largish pea. Coming cautiously 

 to the mouth of the hole, the crab waited to reconnoitre, 

 and if satisfied that no enemy was near, it would venture 

 about its own length distant from the mouth of its hole ; 

 then rapidly taking up particles of sand in its claws or 

 chelae, it deposited them in a groove beneath the thorax. 

 As it did so a little ball of sand was rapidly projected as 

 though from its mouth, which it seized with one claw and 

 deposited on one side, proceeding in this manner until 

 the smooth beach was covered with these little pellets, 

 or pills, corresponding in size to its own dimensions and 

 powers. It was evidently its mode of extracting par- 

 ticles of food from the sand. I made many attempts to 



