288 MIGRATION OF ANIMALS. 



residence is in the tropical climates of Africa and America 

 Land-crabs generally frequent the mountainous parts of the 

 country, which are, of course, most remote from the sea. 

 They inhabit the hollows of old trees, the clefts of rocks, and 

 holes which they themselves dig in the earth. They are ex- 

 tremely numerous. In the months of April and May, they 

 leave their retreats in the mountains, and march in millions 

 to the seashore. At this period the whole ground is covered 

 with them, and a man can hardly put down his foot without 

 treading upon them. The object of their migration is to de- 

 posit their spawn on the seashore. In their progress toward 

 the sea, like the northern rats, the land-crabs move in a straight 

 line. Even when a house intervenes, instead of deviating to 

 the right or left, they attempt to scale the walls. But, when 

 they meet with a river, they are obliged to wind along the 

 course of the stream. In their migration from the mountains, 

 they observe the greatest regularity, and commonly divide 

 into three battalions, or bodies. The first consists of the 

 strongest and boldest males, who, like pioneers, march for- 

 ward to clear the route, and face the greatest dangers. The 

 females, who form the main body, descend from the mountains 

 in regular columns, which are fifty paces broad, three miles 

 long, and so close that they almost entirely cover the ground. 

 Three or four days afterwards, the rearguard follows, which 

 consists of a straggling, undisciplined troop of males and 

 females. They travel chiefly during the night; but, if it rains 

 by day (for moisture facilitates their motion), they proceed in 

 their slow, uniform manner. When the sun shines, and the 

 surface of the ground is dry, they make a universal halt till 

 evening, and then resume their march. When alarmed with 

 danger, they run backward in a disorderly manner, and hold 

 up their nippers in a threatening posture. They even seem 

 to intimidate their enemies ; for, when disturbed, they make 

 a clattering noise with their nippers. But, though they en- 

 deavor to render themselves formidable to their enemies, 

 they are cruel to each other. When an individual, by any 

 accident, is so maimed that he cannot proceed, his compan- 

 ions immediately devour him, and then pursue their journey, 

 After a fatiguing and tedious march, which sometimes con- 

 tinues three months before they reach the shore, they prepare 

 themselves for depositing their spawn. The eggs still remain 

 in the bodies of the animals, and are not excluded, as usual 

 to this genus, under the tail. To facilitate the maturation and 

 exclusion of the eggs, the land-crabs no sooner arrive on the 



