130 



Didlit'iiiiiis! was the only other form that showed any tendency toward a 

 cousideralile surface increase after midnight, but its morning increases 

 were miicli smaller than those of the evening. Then, too, moonlight had 

 no appreciable effect upon the diurnal movement of any of the Crustacea. 



SrifMARV. 



1. There was comparatively little change in the quantity of plankton. 



2. Diurnal movement was shown by E (nschura, Diaptomus, Cydoys, 

 Daplnuii hi/alina and rctrocurva TMaphdnosoina, Lepiodora, and Corcthra 

 larva?. 



3. These various forms reached a maximum at the surface about 8 

 p. m. 



4. Light is a verj' important factor in the movement of Diaptomus, 

 Cyclops, and Daplniia hynlhia and retrocurva. It is, apparently, not so im- 

 portant a factor in the movement of Epischiira, DapJniid piiUcaria, Lepto- 

 dorn, and Corethra larvae 



5. Diurnal movement was not affected bj- moonlight. 



LITERATURE CITED. 

 Blanc, 1898. Le Plankton nocturne du Leman. H. Blanc. Arch, des sci. 



physiq. et nat, T. 6, 3898. 

 Fordyce, 1000. The Cladocera of Nebraska. Charles Fordyce. Trans. 



Amer. Micro. Soc. A^ol. XXII, pp. ll;)-174, IJMX). 



