166 U.S. NATIONAL MUSEUM BULLETIN 292 



Regardless of where this crab occurs, it responds rapidly to moving 

 objects but apparently totally ignores the pounding and rushing 

 water that may completely cover it. On some of the algae-covered 

 rocks that are exposed, one or more crabs will climb to the higher 

 areas and there, after raising the anterior parts of their bodies, remain 

 motionless. If disturbed, they quickly disappear to the opposite side 

 of the rock from the source of the disturbance, where they wait, 

 sometimes less than a minute, before returning to their original 

 position. If the distvn-bing element does not approach too closely, 

 the crabs wUl repeat their retreat and resumption of their positions 

 several times before scurrying beneath the water. These crabs are 

 not easy to catch; on the seawall it was comparatively simple to 

 get them with a long-handled net, but attempts to snare them from 

 an exposed rock or among the boulders and stones along a rocky 

 beach often proved frustrating or futile if the person was alone. 

 Their habit, on retreating, of wedging themselves into crevices or 

 between stones does permit an easier captiure than if they continue 

 to move, for when they become wedged, they seem little concerned 

 that a part of the carapace and one or more legs may be exposed, 

 and because of this, they can be pinned with a smaU stick and so 

 manipulated with one's fingers that the crabs can be dislodged and 

 withdrawn. Two persons coordinating their efforts, moreover, are 

 much more effective than one. 



In March 1966, near the mouth of the Macoucheri River, Dr. R. B. 

 Manning and Hobbs saw one of these crabs on an uprooted, partially 

 submerged tree trunk, and on nearing it discovered that there were 

 several G. grapsus on the trunk. By approaching the trunk from 

 different directions, the two observers kept the crabs moving from 

 one side of the log to the other and eventually pinned them in crevices 

 or under the observers' hands as the crabs raced by. 



Distribution. — Rocky shores from the Bermudas and southern 

 Florida to Estado de Pernambuco, BrazU (Bermudas, Great Abaco I., 

 Bimini Is., New Providence I., Andi'os I., San Salvador I., Rum 

 Cay, Cuba, Jamaica, Hispaniola, Puerto Rico, Isla de Vieques, 

 Saint Thomas, Saint John, Saint Croix, Dominica, Martinique, 

 Saint Lucia I., Barbados, Trinidad, Islas Los Roques, Bonaire, 

 Curagao, Isla de Providencia, Swan Is.) ; eastern Atlantic from 

 southern Portugal to northern Angola; eastern Pacific from central 

 Baja California to central Chile. 



Dominica Stations: 6, 94, 113-115 (0-15 ft.). 



Remarks. — The only ovigerous female in the Dominican collections 

 was taken in late February. 



