396 



Ponds of this kind form a fresh water "unit of environioeut'" typical 

 for an area covering a part of twenty counties of southern Indiana, a strip 

 of Kentucky and a part of Tennessee. Instead, however, of making a gen- 

 eral study of the faunie of many of these ponds, a typical pond one-half 

 mile northeast of the campus of Indiana Uziiversity has been studied in- 

 tensively. Its fauna has been determined, its physical factors and environ- 

 ment analyzed, and the processes at work determined in part, at least. 



Observations on this pond extend from October. 1908, to June, 1909, 

 and from September. 1909. to September. 1910, with occasional visits from 

 September, 1910. to May, 1911. It was visited weekly or more often during 

 all but the summer months. No observations were made during the sum- 

 mer of 1909. but the pond was visited monthly during the summer of 1910 

 (June 15, July 16, August 12). 



Many other ponds have been examined, but detailed data concerning 

 them have not been collected. The observations on these have been in- 

 corporated in this paper when they made clear facts that could not be deter- 

 mined from this pond alone. 



Aside from presenting a picture of the conditions in this pond, I hope 

 the data collected may furnish a basis for comparison with the larger 

 bodies of fresh water (glacial lakes and rivers), so many of which have 

 been under observation in recent years. 



THE POND. 



The form of the pond may be seen by reference to the map. No. 1. It 

 is oval in shape and has a maximum length of 70 feet and width of 57 feet. 

 Its greatest depth is 46 inches, but this is attained only during the heavy 

 rains of spring. The south, east and north slopes are quite gentle, but the 

 west slope is so abrupt that within one foot of the shore, on the north end 

 of the west side, a depth is attained which is only six inches less than the 

 greatest depth of the pond. The bottom is covered with plant debris mixed 

 with a little fine clay derived from the wash from the slope above the 

 pond. This silt is small in quantity, the slope being slight, the area 

 drained small, and a narrow zone of grass surrounding the pond. 



Location. — The location of this pond may be determined by examining 

 the Bloomington Quadrangle of the United States Topographical Survey. 

 It is 940 feet above sea level and about 150 feet above the floor of the 

 valleys one mile distant. It is about 16 feet below the crest of an old 



