402 REPORT OF THE COMMISSIONER" OF FISHERIES. 



to be a series of leaps, and the animal seems too far above the bottom 

 to be running- upon it; j'et all the legs are in motion except the large 

 first pair. Of the latter, the one on the side toward which the animal 

 is moving is held straight out sidewise, while the other is folded up 

 under the shell. 



METHOD OF CONCEALMENT, 



The coloration of the crab is such as to harmonize very perfectly 

 with the surroundings, and the animal attempts ver^^ little concealment 

 if there are other objects on the bottom. Often, however, a clear, 

 sandy bottom or some oozy pond will be found to be almost alive with 

 crabs which have buried themselves until only their eyes and their 

 antennae are exposed. In thus hiding, the crab goes nearlj- vertically 

 backward into the bottom and then, by a few movements, turns 

 slightly, so that the shell rests at an angle of about 45°. The material 

 above settles down and effaces all traces of the entrance. It usually 

 happens that the bottom affected by the crab is firm enough to render 

 this operation somewhat slovv^ and it rarely attempts to escape pursuit in 

 such a way. It seems probable that concealment is usually adopted as 

 an ambush from which a sudden attack can be made on some passing 

 fish. 



In certain places, notably shallow ponds and streams which become 

 nearly dry at low tide, the crab may be observed to dig rather large, 

 conical holes, apparantly as reservoirs, and to take up its position in 

 the deepest part. The work of making such an excavation often 

 requires two or three hours, usually commencing soon after the tide 

 has begun to ebb strongly and continuing until the edge of the exca- 

 vation is nearly exposed above the water. The animal works from 

 some suitable point, carr\'ing away load after load of material clasped 

 between the large claw and the lower surface of the front of the shell. 

 It loosens up the surface with the tips of its second, third, and fourth 

 pairs of legs, grasps all it can carrj^ and then moves off" a few inches in 

 the direction of the side which bears the load and deposits it so that it 

 will not roll back. Thus the hole is gradually deepened and the sur- 

 rounding circle built up and widened until it has a breadth of about 

 a foot, with a depth of perhaps 6 inches. The crab then settles 

 itself into the sand or mud at the bottom of the hole and waits until 

 the rising tide offers an opportunit}' to move about again. 



The blue crab has ver}^ seldom been seen to come out on land \olun- 

 taril}', although it is able to sustain life for several hours when 

 removed from the water. In low, swampy situations I have occasion- 

 ally seen an individual mo vdng about in the dense grass or hanging to 

 the grass just above the water, and in Miss Rathbun's paper "The 

 Genus Callinectes," there is a description by Mr. Willard Nye, jr., of 

 the migj-ation of a large number of crabs from a small pond to the 



