Pearse—On the Habits of TJca Pugnax. 
793 
mud towers around their openings. These towers were some¬ 
times an inch in height. In the Philippines the writer had 
observed that the fiddler-crabs usually carried the mud exca¬ 
vated from their burrow eight or ten inches away, and it was 
noticeable that the Massachusetts fiddlers usually piled such 
mud close to their door-ways (fig. 2), contrary to the observa¬ 
tions of Smith (Stebbing, ’93, p. 90). The crabs dug most 
actively when the tide was falling. Then burrows which had 
caved in or been partially filled were repaired. In digging, 
Pig. 2. TJca pugilator.. A female at the mouth of her burrow. Drawn 
from a photograph taken at Falmouth, Massachusetts. 
dirt was scooped up with the walking legs of one side and car¬ 
ried behind the body (fig. 3). A detailed description of 
methods of excavating and carrying dirt has been given in a 
former paper (Pearse, ’12), and Stebbing (’93) reviews Smith’s 
earlier observations. Only once was a crab seen to use his great 
chela in digging. This was when a piece of shell blocked his 
way; he turned around, reached down the hole, and removed 
the obstacle with his chela. 
Sometimes, when the tide had washed the dirt away at the 
mouth of the burrow so that the opening was too large to suit the 
owner, mud or other material was carried to it and smoothly 
plastered down with the walking legs until the size was proper. 
Each hole was usually plugged just before the rising tide 
