794 Wisconsin Academy of Sciences, Arts, and Letters. 
reached it and remained closed while it was covered with water. 
Where the soil was fairly firm a crab would gouge a plug out 
of the beach and pull it down into the mouth of his burrow 
as he descended in such a way as to completely close the open¬ 
ing. On a softer beach a crab carried two or three pellets of 
mud which were placed about the opening of his hole so as to 
partly close it; then he sidled through the narrowed space and 
pulled the mud down with the walking legs of one side (fig. 4) 
so as to nearly close the hole. The legs were then withdrawn 
and dirt was pushed up on the inside so that no aperture was 
Fig, 3. Uca. pugilator. Males carrying loads from their burrows. In 
A the fiddler is facing the observer and walking toward the left. 
He carries his load with the first three legs of the left side. 
B show:s a male carrying a load away from the observer. 
left. Fiddlers seemed to feel that the necessity for having 
their burrows closed when the tide came in was very urgent. 
Once I pulled up all the grass on a thickly populated area about 
six feet square and chased all the crabs into their holes; then I 
sat in front of this open space while the tide came in and cov¬ 
ered the mou ths 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 grabbing one or more pel¬ 
lets of mud, plugged their holes. Other animals that were ob¬ 
served to be active when the tide came in, and which might 
have harmed the fiddlers, were ribbon-fish, minnows, green 
crabs, and prawns. 
Fiddler-crabs usually fed on the wet beach above the water, 
and the position of their burrows nearer high than low tide 
mark, gave them the maximum amount of time for such ac- 
