16 Records of the Indian Museum. [Vou XVIII, 1919.] 
From this report it is evident that considerable amounts of 
salt are present even in waters that are potable, as that of the 
Hamun near Lab-i-Baring; that the salt is not merely sodium 
chloride but of mixed composition, and that its composition varies 
greatly even inthe same part of the Hamun in different circum- 
stances. I have already noted the changes in salinity produced in 
the water by a cessation of the normal wind (p. 13, antea). In 
both samples from the Hamun salts of sodium are the most 
prevalent, but salts of magnesium, which are usually more dele- 
terious to animal life, are present in considerable quantity, and in 
one sample those of potassium are also fairly well represented. 
The sample of water from the small stream was taken about a 
hundred yards up from the beach of the lake, in a little gully in 
the clay cliffs. The stream was a very small one and rose in 
clay among small hills at no great distance from the lake. We 
may take it as representing a solution of the soluble salts in the 
clay of the cliffs. 
The salt from the margin of the Shelagh river, on the one 
hand, represents the offscouring! of the whole Hamun system. 
Here magnesium is poorly represented, while both sodium and 
potassium are present in fairly large amounts. 
We have as yet no data, therefore, to estimate the differen- 
tial effect of water of different chemical composition on the 
aquatic fauna of different parts of Seistan, and, indeed, to arrive 
at any results of the kind would necessitate a very long and arduous 
investigation carried out through the seasons and under all pos- 
sible conditions of flood and the reverse. All that can be said is 
that the aquatic fauna throughout the country lives in abnormal 
and variable types of environment so far as the composition of 
the water is concerned. 
! It cannot, however, be composed of the same proportions of the different 
salts that occur in the water in solution, for some salts crystallize out before others. 
