Figure 210. — Tips of right abdominal appendages of adult 

 males, hairs omitted ; A, Uca pugnax, anterior view ; B, 

 Uca minax, anterior view ; C, Uca pugilator, anterior 

 view; D, same, lateral view (after Crane, 194.3). 



die of orbit. Anterolateral angles slightly pro- 

 duced, continued backward and inward as a low, 

 well-defined ridge, and across entire frontoorbital 

 width. Front about two-sevenths of frontoorbital 

 width, margin regularly arched. Orbits large, 

 open, upper margin sinuous and oblique, lower 

 margin dentate. Eyestalks long, slender. Anten- 

 nule and antenna small. Merus of second maxil- 

 liped with between 10 and 20, rarely 25, spoon- 

 tipped hairs. 



Chelipeds in male very unequal, in female equal 

 and of small size. Large cheliped of male rough; 

 merus with granulated rugose lines outside, lower 

 margins granulate. Carpus and palm tuberculate 

 outside; inner surface of palm with oblique row 

 of granules leading from lower margin to carpal 

 cavity; a short row leading down from ridge of 

 proximal half of upper margin; area between 

 crests coarsely granulate or tuberculate and with 

 tuberculate ridge running along finger from tip to 

 internal distal border of palm. Fingers long, slen- 

 der, widely gaping; immovable finger usually 

 with one large tooth near middle, inferior border 

 nearly straight, tip sometimes depressed, trun- 

 cate; dactyl evenly denticulate and with irregu- 

 larly placed large tubercles, strongly curving 

 downward past tip of opposed finger. Walking 

 legs with carpal and propodal articles hairy. 



Measurements. — Carapace: male, length, 15 

 mm. ; width, 23 mm. 



Variations. — There is a tendency toward de- 

 crease in size in the southern extremity of the 

 range (Tashian and Vernberg, 1958). 



Color. — Carapace of male dark greenish olive, 

 middle and anterior portion mottled with grayish 

 white; front variably light blue between and 



above bases of ocular peduncles, margin tinged 

 with brown ; large cheliped lighter than carapace, 

 pale brownish yellow at articulations and along 

 upper edge of dactyl, fingers nearly white along 

 opposed edges; ocular peduncles and eyes much 

 like dorsal surface of carapace; smaller cheliped 

 and legs somewhat translucent and thickly mot- 

 tled with dark grayish olive; sternum and abdo- 

 men mottled ashy gray. Females less mottled with 

 white dorsally, and without blue on front (vari- 

 ous authors) . 



Habitat. — Pearse (191-1) recorded this species 

 as living primarily on intertidal flats of mud or 

 clay among the roots of Spartina, but overlapping 

 to some extent the sandier habitat frequented by 

 U. pugilator. He found the maximum number of 

 burrows about 2 feet below high-tide mark, and 

 often the burrows had mud towers at the mouths 

 when the beach was littered with debris. Crane 

 (1943) observed "shelter building" in this species 

 to be in its most rudimentary form among the 

 Ucas. She found that in a mixed population of 

 U. pugnax and U. pugilator. U. pugnax always 

 chose the side of any surface irregularity for a 

 hole entrance in preference to flat ground. Pearse 

 (1914) found burrows extending fo 2 feet in 

 depth and terminating at the water level. Teal 

 (1958) reported burrows on Georgia Sea Islands 

 to be in situations similar to those observed by 

 Pearse, on low levees bordering tidal creeks dr 

 farther from creeks in firm, marshy ground some- 

 times covered only at spring tides. Schwartz and 

 Safir (1915) found U. pugnax burrows on a 

 muddy substrate well shaded by marsh vegeta- 

 tion; hence, continually moist. P. pugnax digs 

 most actively when the tide is falling, and often 

 hastens to plug burrows when the tide is rising to 

 cover the burrow mouths (Pearse, 1914). 



Type locality. — New Haven, [Conn.]. 



Known range. — Cape Cod, Mass., to near St. 

 Augustine, Fla. (Tashian and Vernberg, 1958) ; 

 northwest Florida to Texas (Hedgpeth, 1950). 



Remarks. — Like the preceding species, U. pug- 

 nax is an abundant and easily accessible, rela- 

 tively large decapod which has received the at- 

 tention of numerous students. Only information 

 of greatest general interest can be mentioned here. 



The fossil record for this species extends only 

 into the Pleistocene of New Jersey and Delaware 

 (Rathbun, 1935). 



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