1g2t.] N. ANNANDALE: Fauna of Seistan. 239 
Poiyzoa.—Lophopodella carteri was the only member of this 
group observed. Its geographical range is now known to be exclu- 
sively Asiatic, but to extend from Eastern Persia to Japan, the 
Chinese and Japanese race being slightly differentiated. It is not 
by any means always associated with Oligochaete worms, but a 
Chironomid larva not infrequently establishes itself at the base 
of the colony. 
DELTAIC FAUNA OF THE HELMAND AND ITS 
EFFLUENTS. 
We were unable to visit the main branches of the Helmand in 
its inland delta, but collections of fish and molluscs were made in 
this region by Sir Henry MacMahon and other officers of the 
Seistan Arbitration Commission. ‘The fish they obtained were :— 
Scaphiodon macmahont, Discognathus phryne, Schizothorax zarudnyt, 
Schizopygopsis stoliczkae, Nemachilus stoliczkae, Adiposia rhadinaea 
and A. macmahoni. Of these only three (D. phryne, Sch, zarudnyt 
and A. macmahoni) were found in the smaller streams of Seistan. 
The molluscs collected by the Commission in the Seistan delta 
were Vivipara helmandica,' Lamellidens marginalis and Corbicula 
fluminalis. Of the first of these only single empty shells were 
found by us in other parts of Seistan, except for a number of com- 
pletely bleached specimens found in a flood-deposit. There is, 
therefore, some reason to regard the species as peculiar to the 
estuaries of the Helmand, as it has not been found except in Seistan 
and the immediate vicinity to the east. The two bivalves are 
common throughout Seistan, in which the Lamellidens has become 
differentiated into a distinct race (vhadinaea). Shells from the 
Heimand are thinner and smaller than those from other parts of the 
country. The Corbicula is remarkable for its extreme variability. 
We examined smaller streams of the deltaic system of the 
Helmand in the immediate vicinity of Nasratabad, near the ruined 
city of Jellalabad some 12 miles to the north and at Chilling consi- 
derably futher south. Where the water was actually flowing the 
fauna was very scanty, but the high clay banks were full of 
bleached shells of Corbicula fluminalis and often of Limnaea gedro- 
siana and the diferent Planorbidae found in the country. 
Insect-life is usually scarce in such streams, but a noteworthy 
feature of those of Seistan is that the Hydrometridae often seen on 
the surface of the stiller pools are replaced, at any rate in winter, 
by Diptera of the family Ephydridae, which were often observed in 
large numbers resting on the surface film. Mr. Brunetti’ has 
described a species (Halmopota viridescens) from Seistan that 
‘*skates’’ much like Gerrits. 
Near Jellalabad we found the Randa stream practically dry, 
except for shallow pools left in the bed and completely isolated. 
! See Annadale, Rec. /nd. Mus. XIX, p. 114 (1920). 
? Brunetti, Rec. Ind. Mus. XVI, p. 300 (1919). 
