152 Trans. Acad. Sci. of St. Louis. 



River, and several lagoons and numerous ditches. The 

 brick-yard ponds, the ages of which varied from less than 

 a year to more than twenty years, lay in a flood plain ; but, 

 since there had not been a large flood for twenty years, 

 they furnished an excellent opportunity for the study 

 of the succession of entomostracan life in fresh water 

 ponds. When the work had been in progress a few 

 months, there occurred a large flood, which, temporarily, 

 turned all of these ponds into one vast lake. This com- 

 mingling of the waters of the several ponds defeated the 

 most important aim of this series of studies. For this 

 reason, no mention of the relative ages of the different 

 ponds is made in this communication. Since no collec- 

 tions were made at the time of the flood nor for several 

 weeks after it had completely subsided, it is thought that 

 the data giving the entomostracan associates of each form 

 are reliable. 



The tables that are found in the body of this communi- 

 cation record things as they were in Augusta at the time 

 of this investigation; but, they do not pretend to predi- 

 cate what must be the conditions elsewhere. Indeed, since 

 the period of study extended over only a little more than 

 one year, it would be claiming too much to insist that the 

 conditions here recorded must be invariably the case even 

 in Augusta. However, such facts as are recorded are 

 positive and it is thought that they will be of some value 

 to future students of the ecology of the Entomostraca. 



One fact that I noticed deserves more than passing at- 

 tention. Not once in my Augustan experience did I find 

 a cladoceran bearing "winter eggs." It is well known 

 that, in warm climates, the Cladocera do not form "win- 

 ter eggs" ; but, since many of my collections were made in 

 water with a temperature of a little above zero centi- 

 grade, the result just recorded was not expected. In- 

 deed, I often broke a thin layer of ice in order to make 

 my collections. In Ohio, where the winters are much 

 more severe than they are in Augusta, I have often found 

 cladocerans bearing "winter eggs" in water that was 



