436 University of California PuhUcations in Zoology [Vol. 16 



capacity after the maimer of Yerkes and Huggins, and Spaulding 

 working with crayfish, earcinus and hermit crabs. Accordingly I 

 made a labyrinth consisting of a board twelve inches square with a 

 three-fourths inch guard around the sides. In the middle of one 

 side was an opening through which the sand-crabs might pass into the 

 sea water and sand. The crabs were liberated at the opposite end of 

 the board so that a reasonable amount of activity on their part would 

 cause them to drop through the hole into the water; but the vitality 

 of the animals decreased rapidly, so the experiment in the air was 

 abandoned. Then a series of similar experiments in sea water was 

 attempted, but entirely without positive results. A labyrinth was 

 arranged with an opening through which the crabs could pass into 

 moving water and sand, presumably their optimum habitat. In spite 

 of the fact that the opening was toward the window, the animals 

 showed no capacity to "learn" the way out, but, on the other hand, 

 appeared in successive experiments to lose interest in getting out of 

 the labyrinth, even though a moderate amount of activity would take 

 them out and into the sand and running water. Some of the animals, 

 as soon as liberated, swam directly through the opening; others re- 

 fused to move for hours and even days. Some died during the experi- 

 ment, some became indisposed, thus impairing to that extent the value 

 of the experiments. Only eleven of the twenty original animals were 

 used throughout the series. 



Table Showing the Total Length of Time Spent in the Labybinth by All 

 THE Animals 



No. of No. of 



Exp. Seconds Exp. Seconds 



1 2935 6 (3 substituted) 5151 



2 13535 7 6679 



3 3706 8 7618 



4 (3 substituted) 20208 9 _ 93408 



5 (1 substituted) 12900 10 (2 substituted) 10603 



It appears that the range of stimuli which Emerita analoga 

 experiences is comparatively narrow. In nature these animals en- 

 counter a range of temperature not exceeding 18° F, and the chemical 

 composition and oxygen and carbon dioxide content of the water is 

 presumably rather constant, because the water in the San Diego 

 region comes by an upwelling movement from the bottom of the ocean 

 (McEwen, 1915). Also the physiographic character of the beaches 

 which Emerita inhabits is noticeably uniform. Corresponding to this 



