THE HABITS OF FIDDLER-CRABS. 121 



see that he made any effort to return during the twenty-nine 

 days he was watched. Number 8 dug a new burrow where he 

 was placed and occupied it for two days; on the third day he 

 had returned to his old haunts, but was not occupying his orig- 

 inal burrow and had dug a new one 45 centimeters above it; 

 on the fourth day he was often seen to enter his original hole, 

 although he continued to excavate the one he had started the 

 day before; from the fifth day he occupied the burrow he had 

 started on the third and his original burrow was allowed to 

 become filled with mud. Number 4 wandered about for some 

 little time, frequently going to the tops of the little mounds 

 of earth as if looking about. He did not move directly toward 

 his burrow ; in fact, he sometimes went in the opposite direction, 

 but after about an hour he had returned to it. Number 7, an 

 Uca annulipes, dug a burrow where he was placed and occupied 

 it for twenty-two days; during this time his original burrow 

 had become completely filled; on the twenty-third day he had 

 returned to his original station and dug a new hole within 30 

 centimeters of his original home. 



It was by no means easy for a strange fiddler to make his way 

 among his fellows through a densely populated portion of the 

 estero. Dangers beset him on every hand. Number 5, a good- 

 sized Uca rathhunse, was captured at 1.56 in the afternoon, and 

 thrown 6 meters from his hole dov^Ti a small bay. He was an 

 unusually timid individual, dodging into one hole after another 

 and investigating his surroundings from time to time from the 

 tops of hillocks; at 2.59 when he had progressed 2 meters 

 toward his own hole, he unfortunately entered the burrow of a 

 male Uca marionis nitida and emerged in a few moments shorn 

 of most of his legs; only the small chela remained on the left 

 side and the second and fourth walking legs on the right side. 

 He hobbled into a shallow burrow a little way up the bank. 

 Next day his cleanly picked "bones" lay bleaching on the flat. 



Of the 11 crabs moved to new situations, 5 were not seen again, 

 1 was known to be killed (others may have been) , 3 dug burrows 

 in new localities, and 3 returned to their original homes. Of 

 the 3 that dug new burrows, 1 was behind a high grass-covered 

 ridge, but in the other 2 instances the fiddler's view of his old 

 habitat was unobstructed. Three crabs showed a strong homing 

 propensity and the fact that this did not appear in 3 other cases 

 may have been due to an inhibiting factor or factors, such as 

 the danger of travel or the lack of acute vision in certain indi- 

 viduals. It is also possible that there may be individual dif- 

 ferences in the ability or inclination to form place associations. 



