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U.S. NATIONAL MUSEUM BULLETIN 292 



Ecological notes. — Undoubtedly this small anomuran crab is 

 much more abundant on Dominica than indicated by our single 

 record on the south side of the isthmus that adjoins Scotts Head to 

 the mainland (pi. 3a). Here, above the high-tide line on February 27, 



Figure 32. — Petrolisthes quadratus, male (carapace length 4.7 mm) from Dominica station 



110. 



1966, Dr. R. B. Manning and Hobbs were collecting along the cobble 

 beach searching for Geograpsus lividus and Cyclograpsiis integer. In this 

 area, the rocks, 1 to 10 inches in diameter, are pUed upon one another 

 to a depth of one foot. In the splash zone, near and at the sand level, 

 Petrolisthes quadratus was common, outnumbering Geograpsus by far 

 and as abundant as Cyclograpsus, if not more so. A foot or so up the 

 beach from where Petrolisthes was most numerous, Cyclograpsus 



