Tur Brotocy oF EPHYDRA SUBOPACA LOEW 565 
The water in all these pools, as well as in the overflowed areas, remains 
stagnant all the time. When rain is in excess, water may flow into them 
from the near-by ditches or from some areas that are located on a higher 
level; but throughout the greater part of the season the stagnant condition 
is seldom disturbed. The quantity of water in these pools is decreased 
by evaporation during dry weather. The pools themselves, however, 
did not dry up during the seasons of observation. Being so limited in 
area and so sheltered in location, the surface of the pools is not likely to 
be disturbed by the wind. 
Although situated close to one another, the density and salinity in the 
pools have noticeable fluctuations and increase from north toward south 
in their range; this is perhaps due to their gradual approach to the spot 
where the loading of salt takes place, which is near Pool F. The follow- 
ing shows the difference: 
; Salinity 
Density (per cent) 
Pool De er ey a na Pe ce 
August |September} August August 
10* 22t 16t 168 
A 1.5 4 3.90 1.90 
B 2.0 5 1.76 2.28 
C 4.0 6 2.68 5.35 
D 5.0 6 4.20 6.84 
E (C3()) al Diese areca? 5.58 9.70 
F MRO Piensa at 7.40 9.70 
Us tices tee lad coe aee uh Pane a oe OB i eevonust saree ieee en ane 
Tease fy nye ey aati ee eet ar 2 sD eae es od dia Ieee eset 
*Determined in the laboratory. 
{Determined in the field. 
tAnalyzed after one day in the laboratory. 
§Analyzed after being kept for three days in the laboratory. 
BIOLOGICAL CONTENTS OF SALT POOLS 
As the pools are so limited in size and since none of them have been 
in existence for more than a year, it is only natural that no large plants 
have ever been found growing in them. Moreover, the salinity and density 
of the water account for the total absence of some larger animals that com- 
monly inhabit fresh water pools. The only fauna and flora that are com- 
mon here are plancton forms, the plants of which serve as food through- 
