Ovigerous females have been observed near 

 Woods Hole, Mass., from July 4 to July 15 

 (Pearse, 191-4), wandering about over the ground. 

 Farther south the spawning season is more ex- 

 tended, from early July to mid-August in New 

 Jersey (Crane, 1943), and as early as May 21 at 

 Long Lake, Tex. (Hedgpeth, 1950), and in April 

 in northeastern Florida (U.S. National Museum 

 records). On Long Island, N.Y., the peak of 

 spawning occurs in August (Schwartz and Safir, 

 1915). Crane (1943) thought it likely that in the 

 region near New York two breeding times occur, 

 one in July and the other in August. 



The larval and postlarval stages are discussed 

 in the remarks on U. pugilator. Hyman (1920) 

 secured ovigerous females for hatching of eggs by 

 digging them from burrows. He found the first 

 zoea of V. pugnax to resemble closely that of U. 

 pugilator except for smaller size of the former. 



Schwartz and Safir (1915) found the food of 

 Ucas to consist largely of minute algae left on 

 sand by the outgoing tide. Such algae were picked 

 up by means of the small cheliped in males; fe- 

 males, using both small chelae, secured more food 

 in a given time than males. The small chelipeds 

 seemed sensitive to such food, for they were 

 dragged along on the sand while the animals 

 searched for food. Much sand was taken up with 

 the food. Rapidity of movement of the small 

 chelipeds to the mouth was timed and found to be 

 from 24 to 26 times a minute in males, and from 

 74 to 92 times per minute in females. Teal (1958) 

 found that U. pugnax frequently feeds under- 

 water, and that it often remains outside burrows 

 and feeds as the tide rises. This species can sub- 

 sist on bacteria and organic debris. Miller (1961) 

 in his well-illustrated study considered U. pugnax 

 to be intermediate in development of spoon- 

 shaped hairs on the mouth parts and, therefore, 

 more ubiquitous in choice of feeding substrates 

 than its congeners in the Carolinas. Great detail 

 is given in this study. 



In experiments on salinity tolerance, Teal 

 ( 1958 ) found that 50 percent of U. pugnax placed 

 in fresh water died within 1.5 days. In water of 



7 %o> 50 percent mortality occurred after 3 days. 

 Given a choice of fresh or 30 °/ 00 , U. pugnax chose 

 salt water. Teal concluded that these data are 



consistent with the general distribution of the spe- 

 cies, which is restricted to tidal marsh. 



Given a choice of sand or mud substrate above 

 or under water, U. pugnax burrowed only in mud 

 without any reference to water level, and com- 

 petitive species of Uca had no significant effect 

 on numbers of burrows dug. When restricted to 

 the relatively high Salicomia-Distichlis marsh, U. 

 pugnax survived less well than U. pugilator. 



Respiration rates for U. pugnax are higher un- 

 derwater than in air (Teal, 1959), probably be- 

 cause of increased activity necessary to ventilate 

 the gills. 



At normal habitat temperatures, U. pugnax 

 (=rapax) from Trinidad showed a higher meta- 

 bolic rate than from localities in the United States 

 (Tashian, 1956). Tashian found that there is a 

 decrease in sensitivity to temperature change from 

 southern to northern populations, along with an 

 increase in tolerance to low temperature. Teal 



(1958) found that temperatures experienced in 

 nature are not limiting factors in distribution of 

 U. pugnax in Georgia, though high temperatures, 

 near a lethal level occur at times in summer. He 



(1959) concluded that among marsh crabs studied 

 (see "remarks U. minax''), U. pugnax exhibits 

 the most highly developed thermal acclimation, 

 and its abundance on the marshes may be ex- 

 plained in part by its ability to regulate its 

 metabolism over a wide range of temperature. 

 Vemberg (1959) and Vernberg and Tashian 

 (1959) reinforced this conclusion, showing that 

 U. pugnax exhibits a marked tendency to demon- 

 strate seasonal thermal acclimation. Brett (1960) 

 showed that the daily oxygen-consumption cycle 

 is considerably modified by locomotion of the 

 crabs. Gray (1957) found gill area per gram of 

 weight in U. pugnax to be lowest among the East 

 Coast Ucas. 



Crane (1943) observed hibernating U. pugnax 

 in New Jersey, where the burrows were weathered 

 open along the muddy banks of small creeks and 

 could only have been submerged at spring tides. 

 In March at air temperatures of 1.7° to 5.5° C, 

 the immobile crabs were found from the burrow 

 mouths to about 4 inches below the surface. Slight 

 warming in the hand or in the sun elicited fairly 

 rapid movement. 



In another vein, Passano (1960) found an in- 

 verse correlation between temperature and pro- 



MARINE DECAPOD CRUSTACEANS OF THE CAROLINAS 



231 



