l-'ll] Esterhj: Vniical Distributio)i of Eucalanus. 7 



sented here does not show that this species exhibits diurnal migra- 

 tions, there is a very evident set of movements that are certainly 

 as puzzling, and even harder to explain. This behavior is sug- 

 gestive that diurnal migrations may be in a measure protective, 

 since Eucalanus is adapted in other ways to the conditions of 

 existence in the plankton. At any rate, this possibility deserves 

 further investigation. 



Occidental College, Los Angeles, California. 

 Transmitted February 1, 1911. 



BIBLIOGRAPHY 



Juday, C. 



1904. The diurnal movement of plankton Crustacea. Trans. Wise. 

 Acad. Sei. Arts and Letters, 14, 534-568. 



Morgan, T. H. 



1903. Evolution and Adaptation (New York and London, Macmillan), 

 xiii -\- 470, 7 figs. 



Steuer, A. 



1910. Planktonkunde (Leipzig and Berlin, Teubner), xv -|- 723, 1 pi., 

 365 tigs, in text. 



