74 College of Forestry 
ANIMAL LIFE. 
MOLLUSCA. 
Elliptio complanatus, rare, two 
specimens found; emigrants from 
the next station. 
Lymnea stagnalis lilliana, 
mon, on bottom and plants. 
Lymnea stagnalis lilliane, eggs on 
stems of plants. 
Galba catascopium, abundant on 
bottom and plants, a migrant 
from station XXX. 
com- 
Planorbis trivolvis, var., abundant, 
on bottom and plants. 
Planorbis campanulatus, not com- 
mon, on plants. 
Physa ancillaria warreniana, not 
common, on plants and bottom. 
Succinea retusa, in pool on Water 
Wiilow. 
INSECTA. 
Back-swimmer (Notonecta wndu- 
lata), Common. 
Water-strider (Gerris  buenoi), 
common. 
Small Water Bug (Belostoma 
flumineum), nymph, common. 
Water-scavenger Beetle (T'ropister- 
nus glaber), abundant. 
Water-scavenger Beetle 
drus cinctus), common. 
(Philhy- 
Preaaceous Diving Beetle (Lacco- 
philus maculosus), abundant. 
Dragon-fly nymph (A?schna_ spe- 
cles). 
Diagon-fly nymph (Gomphus sordi- 
dus). 
Damsel-fly 
species). 
Damsel-fly (Hnallagma species) . 
Nymph. 
nymph (Hnallagma 
It is probable that such species as Galba catascopium and 
Elliptio complanatus are emigrants from the next station, as 
there are one or more wide connections between this pool and 
the open lake. In times of storm or high water the barrier 
must be covered with water and is of little avail as a barrier. 
The Planorbis trivolvis is not the large, narrow form typical 
of swampy ponds, but a wider, smaller form, evidently closely 
related to binneyt. 
It is evident from a study of the habitats on Frenchman 
Island, that a rapid change is going on, and that the environ- 
ments are in a transition stage from open lake to swamp habi- 
tats.. Station X XX indicates how this may come about by 
the formation of a lakeward barrier which more or less effec- 
tually bars the rough water of the open lake. This area 
becomes inhabited by those animals, insects and mollusks, 
that thrive best in calmer water. When such a habitat 
becomes entirely closed to the lake, preventing the influx of 
fresh water, a true swamp takes the place of the lake-shore 
type and the vegetation and the animal life change accord- 
