Baker—The Fauna of The Lake Winnebago Region. 127 
habitat. As observed in Oneida Lake (Baker, 1918, p. 151) many 
of the animals were of a peculiar green color due to the algae 
they had eaten. Even the shells of mollusks appeared green when 
containing the living animal. 
Habitats in Water Deeper than Two Meters (Table 1.) Be¬ 
yond the two meter contour both plant and animal life becomes 
greatly reduced in both number and kind. Upright plants were 
not found in Lake Winnebago below three meters. The fauna cor¬ 
respondingly decreases. Among Naiades only one species was 
found deeper than 3.4 meters, Lampsilis luteola rosacea at station 
69 in water 5.2 meters deep on a mud bottom. Sphaerium de¬ 
scends to four meters, and Pisidium alone among Pelecypods fre¬ 
quents the deepest parts of the lake, about six meters, where it is 
abundant. Most of the gastropods disappear between three and 
four meters. Amnicola limosa porata descends to 5.5 meters and 
is abundant; Valvata tricarinata is rare at 6.1 meters. 
There is a rapid decrease in number of species as the depth of 
the water increases. Thus, between 2 and 3 meters, 63 species 
occur; between 3 and 4 meters, 32 species; 4 to 5 meters, 29 species; 
and 5 to 6 meters, 13 species. This decrease is greater for Lake 
Winnebago than for Oneida Lake, the percentages being as fol¬ 
lows : 
Lake Winnebago 
Oneida Lake 
86 per cent. 
60 per cent. 
44 per cent. 
40 per cent. 
2 meters, 85 per cent. 
3 meters, 43 per cent. 
4 meters, 39 per cent. 
5 meters, 17 per cent. 
The depth areas seem divisible into three subregions: Littoral 
to a depth of three meters where rooted plants cease to grow; sub¬ 
littoral to a depth of four meters where Cladophora and other 
' algae cease to grow; and aphytal from four to six meters where 
plant life (except plankton algae) ceases to grow. The decrease 
in plant and in animal life with depth thus appears to be co¬ 
incident. 
The associated animals show aboi^t the same decrease with 
depth as the mollusks, although a greater variety inhabit deeper 
water. Chironomid larvae descend to a depth of over six meters 
and appear to bear the same relation to the associated animals that 
Pisidium does to the Mollusca. Leeches (Glossiphonia and Dina) 
