292 _ Annals Entomological Society of America [Vol. V, 
Pearl, R. 1903. The Movements and Reactions of Fresh-Water Planarians. A 
Study in Animal Behavior. Quarterly Journal of Microscopical Science, 
Vol. 46, pp. 509-714. 
Plateau, F. 1888. Recherches expérimentales sur la vision chez les Arthropodes 
(cinquiéme partie). Bulletins de L’Académie Royale des Sciences, des 
Letteres et des Beaux-Arts de Belgique, cinquante-huitiéme année, 3me 
Serie, t. 16, pp. 395-457. 
Putter, A. 1900. Studien tber Thigmotaxis bei Protistein. Archiv fir Anat- 
omie and Physiologie, Physiologische Abteilung, Supplementband 1900, 
pp. 243-302. 
Radl, E. 1903. Untersuchungen tber den Phototropismus der Tiere. 188 pp- 
Leipzig. 
Romanes, J. G. 1884. Mental Evolution in Animals. 411 pp. New York. 
Severin, H. H. P., and Severin, H. C. 1911. Habits of Belostoma (=Zaitha) 
flumineum Say and Nepa apiculata Uhler, with Observations on other Closely 
Related Aquatic Hemiptera. Journal of the New York Entomological 
Society, Vol. XIX, No. 2, pp. 99-108. 
19lla. An experimental Study of the Death-Feigning of Belostoma (=Zaitha 
Aucct.) flumineum Say and Nepa apiculata Uhler. Behavior Monographs, 
Vol. 1, No. 3, Serial No. 3, pp. 47. Cambridge. 
Sondheim, M. 1901. Wahrnehmungsvermogen einer Libellenlarve. Biolo- 
gisches Centralblatt, Bd. X XI, Nr. 1, pp. 317-319. 
Spencer, H. 1885. Principles of Psychology. 2d ed. Vol. I, 642 pp. New York. 
Uexkull, J. V. 1908. Studien uber den Tonus. V. Die Libellen. Zeitschrift fur 
Biologie, Bd. L, pp. 168-202. 
Weed, C. M. 1889. Studies in Pond Life. Bulletin Ohio Agricultural Exper- 
iment Station. Technical Series, Vol. I, No. 1, Art. II, pp. 4-17. 
Whitman, C. O. 1889. Animal Behavior. Biological Lectures from the Marine 
Biological Laboratory. Wood's Holl, 1898, pp. 285-348. Boston. 
Ecological Laboratory, University of Illinois, January 6, 1912. 
