THE HABITS OF FIDDLER-CRABS. 117 



During the summer, however, 3 males were seen to hold a ball 

 of mud with the two walking legs just behind the large chela, 

 and on one occasion a male carried 3 successive loads in this 

 manner. The males do not use the large chela for burrowing. 

 As has been stated, females dig and carry from the burrow with 

 the first three legs of either side, there being no difference 

 between the legs. In either sex an animal bearing a load walks 

 on the two posterior legs of the loaded side and the four walk- 

 ing legs of the opposite side. The burden is ahvays below the 

 animal as it emerges from the burrow. 



The successive loads of mud are often carried as much' as 

 two-thirds of a meter from the mouth of the burrow; usually, 

 however, to a distance of 25 to 30 centimeters; sometimes they 

 are not carried away at all and may even be built in around the 

 mouth of the hole. At times, all the excavated material is 

 carried to a certain spot at a distance from the mouth of the 

 burro\Y; the writer has seen from 40 to 50 loads thus placed in 

 a neat pile. Some individuals scatter mud over a space of 1 to 

 2 meters, two loads seldom being put in the same place. One 

 individual had 2 dump piles and he varied his labor by carrying 

 a few loads to one, and then a few to the other. The mud 

 brought from the burrow is often spread out flat and searched 

 over for food with the small chela. The rapidity with which 

 dirt is removed from a burrow varies to a considerable degree; 

 a certain individual may bring only one load in a forenoon, while 

 others may work as fast as possible for an hour or more. Dif- 

 ferent fiddlers were seen to excavate as follows : 6 loads in 

 twenty minutes, 16 in twenty-one, 6 in six, 26 in twenty-five, 

 5 in three, 11 in five and one-half; or, these individuals averaged 

 one load every 3.3, 1.3, 1.0, 1.0, 0.6, and 0.5 minutes respectively. 



As has been stated, the burrows are usually closed when the 

 tide comes in. Often the mouth of a hole is prepared by bring- 

 ing in a bit or two of dirt from outside or by carrying some mud 

 from below; such masses are plastered around the mouth of 

 the burrow and smoothed over to make the opening more nearly 

 circular. When all is ready the crab goes a little way off and 

 secures a disk of stiff mud which he carries back to the hole and 

 draws down after himself in such a way that the mouth of the 

 burrow is neatly and completely closed (fig. 2). The "plug" 

 is loosened from the floor of the estuary by pushing the walking 

 legs beneath it, the crab "leaning back" to do so. The males 

 always use the legs of the side opposite the big chela for this 

 work, but the females employ those of either side. As it is 

 carried to the burrow, the plug is held by the first three walking 



