396 
Ponds of this kind form a fresh water “unit of environment” 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 faunze of many of these ponds, a typical pond one-half 
mile northeast of the campus of Indiana University 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 
