396 BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



Ambulatory legs especially hairy on the carpal and propodal 

 joints. 



Color. Dorsal surface of carapace of male very dark greenish 

 olive, the middle and anterior portion mottled with grayish white; 

 the front, between and above the bases of the ocular peduncles, light 

 blue, varying somewhat in intensity in different specimens, and the 

 anterior margin tinged with brown. Large cheliped lighter than 

 carapace, marked with pale brownish yellow at the articulations and 

 along upper edge of dactylus, and both fingers nearly white 

 ylong prehensile edges. Exposed portions of ocular peduncles arid 

 eyes like dorsal surface of carapace. Smaller cheliped and legs 

 somewhat translucent and thickly mottled and specked with dark 

 grayish olive. Sternum and abdomen mottled ashy gray. The 

 females differ from the males in having dorsal surface of carapace 

 less distinctly mottled with whitish and in wanting the blue on the 

 front. (Smith). 1 



Measurements. Male (3836), length of carapace 14.8, width of 

 same 22.5 mm. 



Habits. Makes its burrows only upon salt marshes, but is often 

 seen in great companies wandering out upon muddy or sandy flats, or 

 even upon the beaches of the bays and sounds (Verrill and Smith). 2 

 Usually digs its holes in mud (Pearse). 3 Lives on a muddy sub- 

 stratum which is well shaded by a dense vegetation and hence con- 

 tinually moist (Schwartz and Safir). 4 



Range. From Provincetown and Barnstable, Massachusetts, to 

 Louisiana. 



Material examined. 



Provincetown, Massachusetts; sand; April 14, 1879; U. S. Fish 

 Comm. ; 18 specimens (3828). 



Barnstable, Massachusetts; 1875; U. S. Fish Comm.; 1 male, 1 

 female (4163). 



Cataumet, Massachusetts ; July 22 ; U. S. Fish Comm. ; 9 males, 2 

 females (40793). 



"Woods Hole, Massachusetts: U. S. Fish Comm.; 4 males (40795). 

 1911; U. S. Bur. Fisheries; 15 males, 1 female (43156). 



Vineyard Sound, Woods Hole, Massachusetts; 1911; U. S. Bur. 

 Fisheries; 1 specimen (43192). 



Naushon Island, Massachusetts; 1882; U. S. Fish Comm.: 158 

 males, 18 females (5864). August 15; 7 males, 1 female (40794). 



1 Trans. Connecticut Acad. Arts and Set., vol. 2, 1870, p. 132. 



*Kept. U. S. Commr. Fisheries, vol. 1, for 1871-72 (1873), p. 545 [251]. 



Ann. Kept. Smithson. Inst. for 1913 (1914), p. 416. 



* For a comparison of U. pttffnax with U. pugilator, see Schwartz and Saflr, The 

 Natural History and Behavior of the Fiddler Crab. Cold Spring Harbor Monographs, 

 No. VIII. Brooklyn Inst. Arts and Scl., 1915, pp. 1-24. 



