MALACOSTRACA. DECAPODA. 277 



water with a tremendous clattering, caused by strik- 

 ing one claw against the other. Their shell is in- 

 scribed with numerous irregular lines. 



Ocypode,* the Horseman. 



Rather more aquatic than the true Land-crabs, 

 the Horsemen inhabit the sandy sea-shores near 

 the mouths of rivers. They have short, nearly 

 equal claws, and a very narrow abdomen. They 

 form burrows in the sand, which they inhabit dur- 

 ing the day, coming out chiefly after sunset. They 

 have been celebrated from antiquity for their swift- 

 ness in running over the sand, which is so great 

 that a horse can scarcely overtake them. Bosc ob- 

 served a species (O. Hippeus-\f) in Carolina, which 

 he had some trouble in overtaking on horseback, and 

 shooting with a pistol. They inhabit only warm cli- 

 mates. 



Gelasimus^ the Calling Crab. 



This genus has club-shaped eyes, slender antennae, 

 and unequal claws ; sometimes the right, sometimes 

 the left, being greatly larger than the other. This 

 disproportion, however, answers an useful end, for, 

 retiring into its burrow, the Crab closes the entrance 

 with the great claw, which prevents intrusion, and is 

 likewise ready to seize passing prey. They have the 



* 'flxyj, okys, swift, and vovs, pous, a foot, 

 t 'Iw-fftlif, hippeus, a horseman. 



, gelasimos, ridiculous. 



