128 Wisconsin Academy of Sciences, Arts, and Letters. 
and Oligochaete worms also descend to six meters or more. This 
fauna is not large. Hydra oligactis occurred at two habitats on 
a gravel bottom and Planaria maculata was found in the same 
places; Hyalella was rare in the deeper habitats; Ephemera oc¬ 
curred at 2.5 meters, Caenis at 4 meters, and Hexagenia at 5.5 
meters; Sialis infumata was rare; Corixa and Plea striola, nymphs, 
were rare; Trichoptera (Molanna, Agraylea, Leptocella, Hydro¬ 
psyche and Helicopsyche) disappeared at 3.1 meters. A single 
larva of Nymphula was dredged at a depth of 4 meters on a mud 
bottom. Coleoptera included Psephenus lecontei at 2.8 meters, 
Hydrovatus pustulatus at 4 meters, and Dascyllid larvae down to 
3.4 meters, none common. Hygrobates was found at 2.5 meters, 
and Limnesiopsis at 3.1 meters. 
Lake Butte des Morts (Table 1). 
Lake Butte des Morts is about five miles long and two and a half 
miles wide with a maximum depth of 4.6 meters. It is but a wid- 
ened-out lower portion of the Fox Eiver, though carrying ^so the 
waters of Wolf Kiver and several creeks. Most of the ecological 
conditions of a lake environment are present. Boulder shores are 
rare, occurring on such places as Plummers Point and Sunset 
Point, where, however, sand and gravel are quite as common and 
are usually closely associated with boulders. The shores in the 
bays are usually marshy with an abundant growth of sedge, cat¬ 
tails, and other aquatic plants. In many places this kind of shore 
is fully a quarter of a mile in width. The bottom of the bays is 
usually of mud, clay, or fine sand covered with a thick layer of 
plant debris. Sand occurs along some shores, as west of Plummers. 
Point, as well as on the bottom of the marsh areas at the west end 
near the Pox River channel. The same vegetation occurs as in 
Lake Winnebago. 
About the same kind of mollusks occur in this lake as in Lake 
Winnebago. A few species, as Nephronaias carinata, Amhlema 
costata, and Amnicola limosa, indicate the influence of the Fox 
River fauna. As in Lake Winnebago, the number of species de¬ 
creases with increased depth, 51 species being found between shore 
and 2 meters, 12 species between 2 and 3 meters, and but 3 species 
below 3 meters. Three species make up 53 per cent of the total 
molluscan population, Amnicola limosa 22 per cent, Bythinia 24 
per cent and Valvata 7 per cent. 
