THE CRUSTACEA OF NEW JERSEY. 453 



the mouths of rivers and brooks, and extends up even to places 

 where the water is quite fresh. It usually reaches a large size 

 and is marked with red at the joints of the chelipeds. It is 

 a vegetarian, feeding on the alg?e which grow in muddy salt- 

 marshes. This is often a minute-green algoid plant covering 

 the surface of the mud. The male uses its small claw exclu- 

 sively in obtaining its food and conveying it to the mouth. 

 The female uses either of her small ones indifferently. In en- 

 larging its burrows the crabs were seen to scrape off the mud 

 from the inside by means of the claws of the ambulatory legs, 

 and having formed the mud into a pellet, pushed it up out 

 of the hole by means of the elbow-joint at the base of the 

 great claw, when this is folded down. The crab was also 

 found to construct a regular oven-like arch of mud over the 

 mouth of its burrow. This archway is horizontal and large 

 enough to contain the crab, who quietly sits in this curious 

 doorway on the outlook for his enemies of all kinds. 



This species is the only one found in or about our lower 

 fresh water tidal regions, though it ranges down to perfectly 

 brackish water and is sometimes found associated with Uca 

 pugnax. The burrows are much larger than those made by the 

 latter, often reaching two inches or less in diameter. They are 

 very tenacious and active animals. In New Jersey I have as 

 yet only met with it in the tributaries of Delaware Bay, especi- 

 ally along the banks of Dennis Creek, in Cape May county, 

 near South Dennis. It was also secured at Beesley's Point by 

 S. Ashmeade. I have found it in fresh-water tributaries of the 

 Delaware river just below Newcastle, in the state of Delaware, 

 wdiich seems to be its uppermost range in that river-basin. 



Mr. W. T. Davis found it at Dennisville, N. J., on September 

 5th, 1908, in considerable numbers. He also says that he has 

 found it on several occasions in the meadows along Staten Island 

 Sound side of Staten Island, N. Y. Mr. Alanson Skinner found 

 examples at Watchogue on Staten Island in July, 1907. 



Leidy's examples from Dennis Creek, now dried, are among 

 the largest specimens I have seen. 



