296 INDEX 
Yerkes, R. M., 190, 231, 258, 
intelligence in Carcinus, 
184; in crayfish, 184; in 
frog, 228; in turtles, 230; 
variability of behavior in 
dancing mouse, 133, 184 
Yoakum, C. S., 259 
Yung, E., 190 
Zell, T., 259 
Zeigler, H. E., 114 
Zurn, F. A., 259 
