16 



Trans. Acad. Sci. of St. Louis 



Commensal Vorticellidae {Pyxedium sp., etc.) have 

 been discovered on Scapholeberis mucronata Birge. 

 Explanations of Tables. 



The following tables epitomize the results of field ob- 

 servations. In the tables on seasonal distribution cer- 

 tain months are omitted, those being months in which 

 no field work was done. 



The tables on seasonal distribution, those on distribu- 

 tion according to temperature, and those on distribution 

 according to habitat epitomize the work of four collect- 

 ing seasons; the table giving the distribution according 

 to the hydrogen ion content of the water is the result of 

 only one year's work. 



The centigrade scale is used for temperature; the 

 hydrogen ion content is expressed in PH values. 



The tables record the results of field observations, and 

 contain neither inductions nor deductions. 



Distribution of St. Louis Copepoda From April 1909 



To June 1910 



