Tg2t. | N. ANNANDALE: Fauna of Setstan. 241 
In drift of fragments of reeds, etc., that surrounded most of these 
pools, dead shells of Limnaea gedrosiana and the other common 
molluscs. of the country, including one of the few endemic species 
(Amnicola sistanica), were abundant, with the statoblasts of Lopho- 
podella and the gemmules of the sponges Sfongilla alba and S. 
(Eunapius) carter. 
In most of the pools we found no macroscopic life, but in one, 
in which a broad-leaved Potamogeton was common though not in a 
flourishing condition, Disocgnathus adiscus and young specimens 
of Schizothorax zarudnyi were abundant. Schizocypris brucei were 
also found, but in much smaller numbers. A peculiar form of 
Limnaea gedrosiana was also common in this pool. It is distin- 
guished from the forma typica of the species by its much greater 
individual variability and by the fact that the curve of the outer 
lip of the shell is flattened to a straight line. This mollusc, for 
which the varietal name vectilabrum has been proposed, has been 
found elsewhere only in the Kushdil Khan reservoir in the north 
of the hill-country of Baluchistan. The reservoir is a large, 
shallow artificial lake witha luxuriant submerged vegetation in 
winter, but liable to complete desiccation in summer. ‘The speci- 
mens of the mollusc from Seistan were mostly infected bv the 
common North Indian Oligocheate worm Chaetogaster bengalensts, 
which frequented their pulmonary chamber in large numbers. 
THE FAUNA OF THE HAMUN-I-HELMAND. 
The Hamun-i-Helmand, or rather that part of it which is 
permanently filled with fresh or nearly fresh water, may be divided 
into three zones of life, that of the open lake, that of the reed- 
beds and that of the bare margin. 
The zone of the open lake may be called more appropriately 
the Central Region. It is that part of the lake which is free from 
reeds and always, except in abnormal droughts, contains several 
feet of water. The reed-beds form in winter what is called in 
Persian the matzar or reed-country, but the name maz is applied in 
Seistan particularly to Phragmites, which is the most abundant of 
the three species of which the reed-beds are composed, namelv 
Phragmites communts, Scirpus littoralis and Typha angustifolia. 
In the flood-season a great area in the mazzary is under water and 
even when the water is low, as it is in December, the reed-beds 
extend out into the lake for considerable distances. In discussing 
the fauna of this zone we must, therefore, consider both the species 
living in pools among the reeds and also those of which remains 
are found in a dead or dormant condition in the soil of the nazzar, 
By the zone of the bare region I mean the shore of the lake at or 
just below low-water level at places where there are no reeds. 
THE FAUNA OF THE CENTRAL REGION. In December this region 
is very poor in life, both animal and vegetable. The bottom is a 
stiff, sticky clay which supports but a scanty growth of water- 
plants. A few beds of Potamogeton lucens, none of them at all 
