138 The Ohio Journal of Science [Vol. XXI, No. 5, 



by Mr. C. J. Drake, in his study of that group in Ohio, no 

 systematic survey of its fauna has been attempted, except for 

 the Protozoa, which have been worked out recently by Miss 

 Mabel E. Stehle, (1920). 



Collections were made between March 1 and October 18, 

 1919, at regular intervals of two weeks and with other occa- 

 sional special collections. Realizing that an entire year's careful 

 collecting, or more, would be necessary to get adequate data 

 for an ecological study, the writer does not consider the work 

 an ecological, but primarily a faunal survey, with merely a few 

 ecological notes. 



For purposes of systematic collecting, definite stations were 

 established, all selected with a few of furnishing examples of 

 all types of habitat that seemed possible or worth while to 

 differentiate. Stations are described below (pp. 141-144), 

 indicated on the map (Plate I), and referred to by number in 

 the body of the paper and in the table. 



Collecting was done with a large, fine-meshed, long-handled 

 dipnet, occasionally assisted by a smaller fine sieve strainer. 

 In taking material at any station, water was strained through, 

 the mass cursorily examined for all larger forms, and a good 

 part of the mass of mud, algae, duckweed, or whatever the 

 material harboring the small forms, taken and put into a glass 

 pint or quart jar labeled for the particular station. Water was 

 dipped into the jar to fill it and thus some plankton forms 

 probably secured which would not have been retained in the 

 net. At successive collections the same area in each station 

 was worked. 



In the laboratory each jar was worked over by making 

 many successive dilutions of parts of the entire haul, in a large, 

 shallow glass dish, during which process, all animals were 

 secured with forceps or pipette, and put into large vials of 70% 

 alcohol, labeled according to station and date. This was done 

 at once to prevent injury to specimens in close confinement in 

 the jars. Later each vial was examined, the various kinds of 

 animals separated and put into smaller vials of alcohol for per- 

 manent preservation. Separation could of course, not be done 

 to species with any certainty whatever. The idea was to sep- 

 arate enough to approximate that ideal of having specimens, 

 when identified by specialists, in individual vials unmistakably 

 named to species. 



