Lhe Relation of Mollusks to Fish in Oneida Lake 129 
observed on both sides. Station I, 2, C is an example of a max- 
imum lily pad habitat, 10 individuals represented by 3 species 
being noted (Fig. 37). It was observed that Acella usually 
chose the edge of the leaf for its position, while Physa and 
Pseudosuccinea apparently had no choice, using all parts of 
the surface. In this type of habitat the water is 3-5 feet deep 
and there is usually a quantity of submerged vegetation pres- 
ent. Each leaf averages about eight inches long and they are 
close enough together to figure each leaf as occupying a 
square foot of habitat. The table indicates the variation in 
number of individuals and species on the lily leaves of other 
stations, 
Type 2 is a pure L'ypha habitat, the surface of the water, 
and the bottom as well, being covered with dead Typha leaves. 
The water is from one-to two feet deep. Open spaces of 
water support a duck weed society. Clinging to the dead 
vegetation on the surface 18 individuals representing 5 species 
were estimated in one square foot of surface area, Planorbis 
trivolvis being the most numerous (see Fig. 38). Type 3 
includes those stations in which the water is filled with sub- 
merged vegetation, such as Chara, Potamogeton, Elodea, 
Ceratophyllum, Vailisneria, ete. The water js usually from 
3 to 7 feet in depth. Numerically, this is the most prolifie 
of all habitats. An area one foot square and reaching to the 
bottom (in the spot counted, the water was four feet deep) 
contained 174 individuals, representing 6 species, 147 of 
which were of one species, Bythinia tentaculata. As many 
of these individuals were young and of small size they are 
especially valuable as food for the smaller fish that frequent 
such a habitat. Station XL, in Big Bay, was the poorest, 
producing but 4 individuals of 2 species. 
