562 Cui PInG 
neighboring localities wherever salt pools occur. The larvae and pupae 
live in water of various densities and in a variety of other physical con- 
ditions, but a certain percentage of salt must be present in the water. 
The species can live in fresh water only for a very brief period. The 
species was found living at two places in Ithaca, the first being an old 
salt plant, near the Inlet, where there were two permanent pools, in which 
the water was brownish in color and salty in taste. All stages of the 
species were collected here in the summer of 1916, but unfortunately, in 
the year following, one pool was filled with dirt, while the other one 
became entirely fresh, and no more of this species could be found there. 
The second place where this species was and can yet be found, is at 
the east bank of Cayuga Lake, at the Remington Salt Works, where the 
salt wells are the sources of the overflow of brine water from an intensive 
area. At this place the water is strong in salt, and the pools, ditches, and 
overflowed areas abound in Ephydra subopaca in all stages of develop- 
ment. Throughout the two summers and a part of the winter of 1916- 
17, most of the field observations were made at this latter place and 
practically all the ecological phenomena discussed herein are related to 
this locality. 
At Ludlowville, on the east shore of Cayuga Lake, a fairly wide area is 
flooded at certain seasons by the brine water from salt wells. This con- 
dition is by no means permanent, and the salt water is frequently dried 
up in midsummer. However, in the summer of 1917 this place was 
visited at intervals for making observations and for collecting. Next to 
the permanent pools at Ithaca, the best place, where enormous numbers 
of this species are found and where the permanent pools, ditches, and 
wide, overflowed areas afford excellent opportunities for field work, is at 
Solvay, Syracuse. 
Owing to convenience of location, most of the ecological observations 
were made at the salt pools at Ithaca. There are eight pools, six of which 
are located in series, about one and a half meters apart, situated from north 
to south along the east side of the lake. The six pools are designated as 
A, B, C, D, E, and F. The other two, I and II, are situated farther away 
from the lake shore, toward the east, and along the roadside. In addition 
to the eight pools, overflowed areas, large and small, are scattered here 
and there between the pools, covering an estimated area of forty square 
meters. 
