228 Proceedings of Indiana Academy of Science 
These authors discuss the possible factors governing distribution, 
and reject all except three—enemies, wave action and bottom. I shall 
refer again to this portion of their paper, and discuss these factors in 
order. 
THE HyYDROGRAPHY OF WINONA LAKE. 
Winona Lake is one of the many kettle hole lakes of the region. 
It lies in the center of Kosciusko County, in the mid-northern portion 
of Indiana. It has a maximum length of two miles, and averages three- 
fourths mile in width. Gently undulating moraines in alternation with 
flat peaty, or mucky, areas which represent in large measure extinct 
marsh or lake, prevail in the surrounding terrain. 
The northern and eastern shores of Winona Lake lie close to grav- 
elly moraines, and the middle of the western side even more closely. The 
southern and northwestern shores are separated from high ground by 
more extensive flat areas, which are but little above lake-level, and have 
gone through the lake-marsh succession. In the case of this lake the 
process of degradation through the erosion of the outlet has been ar- 
rested by a dam. Just prior to the mussel survey by Headlee and 
Simonton much dredging had been done at the east, south, and north- 
western portions of the lake. (Fig. 1.) This resulted in a rather pro- 
found alteration of the bottom in some parts, and the elimination of 
some mussel beds. 
Sugar Creek, Cherry Creek, and Pocahontas Creek, springs, and 
artesian wells are the principal sources of the incoming water. The out- 
let is a creek two miles in length which enters the Tippecanoe River 
below Warsaw. Since the:tributaries are small, though steady, mussels 
have not gone above the lake. The latter is purely lacustrine in form 
and marks the upper limit in its drainage system for all bivalves except 
Sphaeriidae. Such has not always been the case, for I have found shells 
at least two miles up Pocahontas Creek. We should expect a rather 
small number of species so near the headwaters of Walnut Creek. Nor 
should we expect to find river mussels so far up. 
Since the lake level has been held nearly constant for many years, 
the shore line has been well stabilized. Also the wave cut terrace is 
now well established, and in most parts of the lake its margin is sharply 
set off from the abysmal portion of the lake in accordance with the an- 
gle of rest of its component materials. Thus the ten and twenty foot 
contours parallel the shore most closely of all. (Fig. 1.) Wave action 
is still at work reducing the sharp points of the shore line, and the most 
sandy and gravelly parts of the terrace are these exposed points; while 
in the coves the bottom merges into mud at a much slighter depth. The 
prevailing storms are northwest. This is correlated with the fact that 
the wave cut terrace of the east shore is everywhere wider than others, 
and that the contours of the west shore lie closer together. Except for 
the sheltered situations the east terrace is swept freer of mud, which is 
distributed farther out in the lake. The southern corners of the lake 
have not yet recovered from the dredging of twenty years ago. The 
south shore receives the wind and waves obliquely from the northwest, 
