Baker—The Fauna of The Lake Winnebago Region. 115 
white disc could be seen only to a depth of a few inches in the open 
lake. This was due largely to the presence of vast quantities of 
phytoplankton which was universally distributed and unusually 
abundant during these months. The wind moved this mass from 
shore to shore. Occasionally some of the bays were free of the 
plankton and the water became fairly clear so that the bottom could 
be plainly seen at a depth of a meter. Almost everywhere the 
water was filled with fine sediment held in suspension. Compared 
with some other lakes the degree of transparency in Lake Winne¬ 
bago is very low. Bkman (1915) gives 18 jneters for Lake Vaet- 
tern in Sweden; Muttkowski gives three meters for Lake Mendota; 
and Baker found between four and five meters in Oneida Lake, 
N. Y. 
D. Pollution 
Lake Winnebago is suffering from some degree of sewage pollu¬ 
tion. Sewage from the City of Oshkosh enters the Fox River and 
is discharged into the lake south of the city. Dredgings made about 
half a mile to a mile and a half south and east of Oshkosh showed 
a bottom of black mud at a depth of 4.6 meters, in which there was 
a large quantity of oil that came to the surface of the water in the 
pail containing the dredgings, forming a thick film. No animal 
life of any kind was found in these dredgings, but near by, outside 
of the channel of the Fox River, bottom life was fairly abundant 
at similar depths. The same conditions that compelled Chicago 
to divert its sewage from the source of water supply is now con¬ 
fronting Oshkosh and epidemics of typhoid or other water-borne 
diseases are liable to occur as the sewage increases in volume and 
becomes mixed with the water supply, which is drawn from the 
lake east of the city, about half a mile from shore, in water less 
than four meters in depth. It is probable that some manufactur¬ 
ing wastes also enter the lake. The sewage of Fond du Lac also 
contaminates the waters of this lake. 
THE MACROFAUNA OF THE LAKE WINNEBAGO REGION 
The region in which lie lakes Winnebago, Butte des Morts, and 
the Fox River provides unusual opportunities for the study of 
ecological variation. The Fox and Wolf rivers, flowing for many 
miles as typical rivers, expand to form large lakes west of Oshkosh. 
Lake Butte des Morts outflows through a wide river at Oshkosh, 
