REPORT ON THE AQUATIC FAUNA OF SEISTAN. 
PREFATORY NOTE. 
The series of papers of which the first instalment is now pub- 
lished will be based mainly on the collections made by Mr. S. W. 
Kemp and myself in Seistan and Baluchistan in November, De- 
cember and January, 1918-19. The main object of our tour was 
to enquire into the etiology of the disease Bilharziasis or Schistoso- 
miasis, and particularly to discover whether the parasite occurred 
in Seistan, or whether any known intermediate molluscan host was 
found to be in that country. For this and other work on the 
zoological aspect of the disease a generous grant of money was 
made by the Council of the Indian Medical Research Fund. So 
far as it was concerned our results were entirely negative; but we 
took the opportunity to make as large and complete a collection 
of the aquatic fauna as the time at our disposal permitted. As 
this fauna is a limited one (7.e. includes few species but large 
numbers of individuals) we were able to obtain a more representa- 
tive set of specimens than would have otherwise been the case. 
Our material, moreover, is supplemented by the specimens col- 
lected by the Seistan Boundary Commission of 1902-03 under the 
command of Sir Henry McMahon. 
To Mr. Kemp my first acknowledgments are due. Indeed, a 
great part of the zoological success of our little expedition must 
be attributed to him. I only regret that it is impossible for his 
name to be more intimately associated with my own in the prepa- 
ration of this report. The reason is the stress of other work 
and the necessity for a visit to Europe on his part. I have also 
to thank the political officers in Baluchistan and Seistan, in par- 
ticular, Mr. B. J. Gould, I.C.S., His Britannic Majesty’s Consul in 
Seistan, Major D. Heron, I.M.S., C.I.E., Medical Officer and Vice- 
Consul, and Major. W. G. Hutchinson, Political Agent, Chagai. 
The officers serving on the Eastern Persian Cordon also gave us 
much assistance in the way of transport and supplies. Babu 
J. N. Bagchi, Head Clerk, Zoological Survey of India, accom- 
panied us and did good work. I have to thank Mr. EK. Vreden- 
burg of the Geological Survey of India for valuable suggestions 
embodied in the Introduction, while Dr. Baini Prashad, Offg. 
Director of Fisheries, Bengal, Bihar and Orissa, has helped me in 
various ways. 
