HABITS OF THE FOUR-HORNED SPIDER-CRAB. 247 



rest on a horizontal surface is shown in fig. 1. The four pairs 

 of walking legs rest upon the ground, the body being carried 

 obliquely, while the two claws are held in such a way that they 

 resemble inverted V'b, and the animal has a peculiarly watchful 

 aspect. Sometimes the anterior and longest pair of walking 

 legs are raised above the ground and stretched out on either 

 side. Very frequently when at rest against a vertical rock the 

 Spider-Crab will place itself in such a position that its body is 

 vertical, the ventral surface of the animal being pressed against 

 the rock, and its hinder portion, together with the three hinder 

 pairs of walking legs, resting upon the ground. The long first 



Fig. 1. — An adult female Four-horned Spider-Crab in a characteristic 

 resting and watching attitude. The hairs are not represented. 



pair, and sometimes also the second pair, of walking legs are 

 then spread out as straight as possible to right and left of the 

 Spider-Crab. When the Spider-Crab assumes this attitude 

 against a rock it is very difficult to detect the animal. A 

 Spider-Crab may sometimes be found in the morning standing 

 in this posture, not against a rock but against the glass front of 

 the aquarium. If such a Spider-Crab be touched, it presses its 

 body against the glass, just as it would have pressed it against a 

 rock, and then begins to sidle away. It does not sidle away over 

 the floor, but along the glass front, of the aquarium, in spite of 

 the alarm which it must feel when the glass is tapped immedi- 

 ately in front of its eyes as it moves along. It was mentioned 

 above that the Spider-Crab will notice the movement of an arm 

 ten or twelve inches away, and it must be well aware of a finger 

 tapping the glass in front of it. The fact that it will press along 

 the glass front, instead of moving away across the floor of the 



