434 University of California Publications in Zoology [Vol. 16 



an effort to test these reactions further several specimens were de- 

 posited on the beach, where the sand was moist, smooth and firm, 

 but sloping toward the sea. Immediately, the creatures all backed 

 down the slope toward the waves, pausing now and then in an effort 

 to burrow. To ascertain whether the direction was determined by 

 the sight of the waves or by the slope, I first made a plat in the sand 

 on the beach sloping decidedly away from the water, and in the center 

 of this placed several individuals. They all moved down the slope 

 away from the water, showing that, in the air at least, they responded 

 decidedly to gravity. I then made in the moist sand, twenty to fifty 

 feet from the water, a smooth, round, firm, level plat about thirty 

 inches in diameter and bounded by a fosse about one inch deep. A 

 carpenter's level was used in getting the plat level. Wlien Emeritae 

 were placed in the center of this plat, their direction of movement 

 was invariably toward the ocean (fig. 1). I performed this experiment 

 several times, making tracings of the movements of the animals five 

 times, using ten animals each time, always with practically the same 

 result. Even building an embankment of sand about six inches high, 

 entirely obstructing the view of the ocean, created no disturbing 

 effect. 



Under these circumstances, a typical reaction consists of a few 

 moments of "death feint" in which the animal lies perfectly still on 

 its back, followed by a quick, righting movement and an attempt to 

 buiTow. Not being successful in this, the animal orients itself with 

 its posterior part toward the water and crawls off in a zig-zag route 

 to the fosse on the water .side of the plat. Sometimes an individual 

 would never revive from the death feint. It is rather difficult to 

 understand why the physiological make-up of these animals should 

 permit them to prolong a death feint in the hot sun to a stage beyond 

 which there is no recovery, without making efforts to escape into the 

 moist sand. It was noticed that a slight mechanical stimulus, such 

 as being touched with a twig, being rubbed by another sand-crab, or 

 being blown upon, was often sufficient to arouse the animals and to 

 make them right themselves and seek safety. 



In order to eliminate any reaction that might obtain from the 

 proximity of the ocean I repeated the experiment on a pile of beach 

 sand that had been hauled and dumped upon an embankment some 

 two hundred feet from the ocean and about thirty -five feet above sea- 

 level, with practically the same result (fig. 2), although in this series 

 of experiments the animals displayed a slight amount of confusion. 



