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U.S. NATIONAL MUSEUM BULLETIN 29 2 



their burrows, and since there were other similar burrows within the 

 area, it is probable that there were no fewer than 20 of these crabs 

 within it. In the same plot there were from 60 to 100 burrows of at 

 least two species of Uca. 



In the Layou locality, several burrows were carefully excavated, 

 and it was found that there is at least one, frequently two, horizontal 

 passages from 3 to 12 inches long, and, descending from one of them, 

 an almost vertical passage approximately two feet deep that always 

 penetrates the water table. The excavated soil piled around the open 

 mouths was never arranged in the form of a neat chimney. Possibly 

 the lack of chimneys is due to the frequent rains on Dominica, which 

 would erode them quickly. 



Figure 76. — Denuded terminal portion of right first pleopod of male Ucides cordatus shown 

 in figure 75: a, posterior view; b, lateral view; c, anterior view. 



Ucides cordatus is almost certainly the second most sluggish crab 

 occurring in terrestrial and freshwater habitats on Dominica. Only the 

 hermit crab, Coenohitus clypeata, moves more slowly. In comparison 

 with the fiddlers, Goniopsis, and Cardisoma, it is almost lethargic; 

 even so, individuals are not easily collected for seldom do they wander more 

 than a foot from the mouths of their biu'rows, and at that distance, 

 they have ample time to make their retreat before the observer can 

 approach them. A small amount of formalin splashed directly on them 

 or poured into their burrows will cause them to come to the surface, 

 where they can be caught. 



Whereas this crab is usually associated with brackish water, it is 

 doubtful in either of the locaUties mentioned above that salt water 

 reaches the areas except during severe storms. 



Distribution. — Southern Florida to Rio de Janeiro, Brazil (Cuba, 

 Jamaica, Hispaniola, Puerto Rico, Saint Thomas, Antigua I., 

 Dominica) . 



