HABIT FORMATION IN THE FIDDLER CRAB 239 



5. It learns slowly, increasing its movements to the open 

 corner with successive trials. 



6. The rapidity of habit formation varies directly with the 

 frequency of the trials. 



7. Sight and touch are the most important factors in the 

 habit forming process, the former predominating. 



8. An animal which formed the habit can avoid a blind corner 

 by turning before reaching the end of an alley. 



9. The habit persists after a lapse of ten days. 



10. The crab can unlearn the habit, although previous ex- 

 perience seems to have no influence on the rapidity of unlearn- 

 ing. 



In concluding, we wish to express our indebtedness to Dr. 

 H. E. Walter for his reading of the manuscript. 



LITERATURE 



Bethe, Albrecht. Das Centralnervensystem von Carcinus moenas. II Theil. 



1898. Arch, fur Mik. Anal., Bd. 51, S. 447. 

 Drzewina, A. Les Reactions Adaptives des Crabes. Bull. Inst. Gen. Psvch., 



1908. 235, 8. 



1910. Creations d 'associations sensorielles chez les Crustaces. C. r. Soc. 

 Biol. LXVIII, 573. 

 Cowles, P. R. Habits, Reactions, and Associations in Ocypoda arenaria. Papers 



1908. from the Tortugas Laboratory, of the Carnegie Institution of Wash- 

 ington. 

 Holmes, S. J. The Evolution of Animal Intelligence. Henry Holt and Company. 



1911. 

 Spaulding, E. S. An Establishment of Association in Hermit Crabs, Eupagurus 



1904. longicarpus. Journal of Comparative Neurology and Psychology, vol. 

 14, p. 49. 

 Yerkes, R. M. Habit Formation in the Green Crab, Carcinus granulatus. Bio- 



1902. logical Bulletin, vol. 3, pp. 241-244. 



Yerkes, R. M. and Huggins, G. E. Habit Formation in the Crawfish, Cambarus 



1903. affinis. Harvard Psychological Studies, vol. 1, 565. 



