10 Records of the Indian Museum. [VorL. XVIII, 
imperfectly understood and calls for further investigation. By 
calculation about ten feet of surface water should be lost annually 
from this cause in Seistan proper, but observations show that the 
actual amount is considerably less. 
The loss of water through occasional failure of the Helmand 
supply is still more important to the aquatic fauna of the Hamun. 
Both fish and molluscs are said to have been abundant at one time 
in the lake, but it dried up completely in 1871 and again in 1903,! 
and since these dates the fauna is believed to have become much 
impoverished. 
There is only one other kind of body of water to which I need 
refer here, viz. the springs that well up in the stony desert sur- 
rounding Seistan. These springs vary considerably in size and in 
salinity. None of them possess any great volume of water and few 
are quite fresh, the majority containing a more or less strong solu- 
tion of magnesium sulphate, which has a devastating effect on the 
entrails of those who drink the water. An exception to this is to 
be found in the spring at Hurmuk, just across the Persian frontier 
and only a few miles from the point at which those of Persia, 
Afghanistan and Baluchistan meet. The water of this spring, 
which is fairly copious, is fresh and is stated locally to be the best 
in all Iran. Whether they be fresh or salt these springs are usually 
devoid of aquatic vegetation other than algae, at most, as at 
Saindak, having a scanty growth of Potamogeton, but a small 
Scirpus often grows at the edge, and the water is usually edged 
with willow trees (Salix acmophylla), perhaps planted. As-a rule 
there is a small pool, more or less artificial, where the water comes 
out of the earth, with a streamlet or mere trickle passing from it 
into the desert and disappearing at no great distance. 
Origin of the Hamun-i-Helmand. 
It would be out of place in the present paper to discuss the 
geological history of Seistan” in any great detail, but there is one 
problem, that of the age of the Hamun, which has too important a 
bearing on the origin of the aquatic fauna to be entirely ignored. 
It has sometimes been assumed that the Hamun is the shrunken 
relic of a great freshwater lake, which has even been compared to 
the Caspian Sea. AsI have already pointed out (antea, p. 4) the 
existence of a lake of practically fresh water in Seistan is to be 
explained by the peculiar course of the Helmand and by the fact 
that the whole system is occasionally flushed into the Gaud-i-Zir- 
reh, and if, as the body of evidence* seems to show, the whole of 
14 Huntington, E., ‘‘The depression of Seistan in Eastern Persia,’ Bull. 
American Geog. Soc. XX XVII, p. 276 (1905). 
2 See Huntington’s account of ‘‘ The Basin of Eastern Persia and Seistan”’ 
in Explorations in Turkistan (Fxpedition of 1903) published by the Carnegie 
Institution of Washington (1905). 
3 There is an extensive literature on this subject. For a good recent sum- 
mary see the chapter on ‘The Ancient Climate of Iran”’ in Huntington’s book 
‘The Pulse of Asia’’ (London, 1907). Blanford’s volume on the Zoology and 
