HABITS OF FIDDLER CRABS PEARSE. 419 



square and chased all the crabs into their holes. Then I sat in front 

 of this open space while the tide covered the mouths of the burrows. 

 Though the crabs were timid and apparently feared me, several of 

 them rushed out when the water came near and, after hastily grab- 

 bing one or more pellets of mud, plugged their holes. 



Fiddlers are very cleanly in their habits, and may often be seen 

 scraping themselves with the small chelipeds or with the walking 

 legs when dirt has accumulated on any part of the body. They are 

 particularly careful of the eyes and eyestalks, and these organs are 

 often folded into their sockets to be cleaned. Mud or debris is not 

 allowed to accumulate about the mouths of the burrows. Fiddlers 

 are often seen moving such matter to some little distance, where it 

 is cast aside or pushed down the holes of other crabs. 



Crabs of either sex move sideways when entering the burrow, and 

 the males usually have the large chela uppermost as they disappear. 

 The holes are, as a rule, of uniform diameter, though they may be 

 slightly enlarged at the bottom, and often turn so as to take a hori- 

 zontal direction. They vary in depth from about 16 to 75 cen- 

 timeters, and usually have water standing in the deeper parts, even, 

 when the tide is out. 



PLACE ASSOCIATION. 



A fiddler usually does not wander more than a meter or two from his 

 hole, and is ever ready to dart into it at the slightest provocation. 

 Occasionally, however, a crab roves as much as 12 meters from his 

 home and returns. Once in the Philippines a TJca marionis nitida left 

 its burrow and dug a new one 4.5 meters away; another individual 

 moved his dwelling place 2.4 meters; but such cases were unusual. 

 Most crabs showed a strong preference for a particular locality. 

 Place association is also manifest when fiddlers carry mud from their 

 burrows. Successive loads are not cast aside anywhere, but are usu- 

 ally carried to a particular spot and laid in a pile. 



A number of crabs were snared and moved various distances from 

 their holes to see if they would return. If the space was less than 

 2 meters, they usually came back at once. At gi'eater distances some 

 crabs dug new holes and reestablished themselves, even though they 

 were in plain sight of their old homes; others tried to return home, 

 and were not able to do so. It is by no means easy for a strange 

 fiddler to make his way through a densely populated portion of a 

 colony. He is set upon by every crab whose hole he approaches, and 

 may lose his claw or even his life in such an engagement. An indi- 

 vidual put down in strange surroundings acts shy and timid. Not- 

 withstanding the difficulties, however, some crabs returned after sev- 

 eral days to the hole they had previously occupied. One individual 

 was moved 6 meters, and returned after 23 days to within 30 centime- 

 ters of his old home, which had been filled up by the tides in tlie 

 meantime. 



