3226 THE JOINTED ANIMALS 



istic is the enormous size of one of the pincers in the male; and it is from the habit 

 of brandishing this claw, as if beckoning, that the name of calling crab is derived. 

 So abundant are these crabs, that they may frequently be seen by the thousands 

 either running over the sand or peering out of their holes. These holes, which 

 are thickly scattered over wide areas, lead into burrows frequently a foot or 

 more in depth. The crabs scrape up a heap of sand, and grasping the pellet with 

 three of the legs of one side, carry it to some distance before letting it drop, then 

 raising their eyes and peering round, dart back to the burrow, scrape together another 

 heap, and persevere in the same manreuvere till the burrow is of the required depth. 

 It was long supposed that the pincers of the male were used as weapons of attack 

 and defense; but, in addition to its size, this limb is noticeable for its bright colors, 

 and Mr. Alcock, who observed a number of males of an Indian species (G. annulipes) 



THORNS ACK CRAB. 

 (Two-thirds natural size.)' 



waving their large claws in the presence of a female, has suggested that their object 

 in so doing is to make a display of their gaudy ornamentation and thus influence 

 her choice of a mate. 



The third family, Grapsidce, contains species which for the most part are 

 shallow- water forms. They are widely distributed, and attract the attention of 

 travelers both on account of their bright colors and their extraordinary activity. 

 Possessing long and powerful legs, tipped with sharp strong claws, they are able to 

 dart among the rocks on the coast with amazing speed, while by means of their 

 flattened carapace and limbs they can slip away into the narrowest clefts and chinks. 

 Unlike the majority of the family, the little gulf weed crab {Planes minutus) occurs 

 in temperate and tropical seas, among the floating weed, and it is said that Colum- 

 bus adduced its presence as an argument in favor of the proximity of land when his 

 sailors were on the verge of mutiny. The crabs of the family Pinnotheridce have 

 the carapace soft and membranous and the orbits and eyestalks are small. An in- 



