248 Records of the Indian Museum. [ Vor. 2aVibiee 
found in slightly brackish water. The Seistan form belongs to a 
distinct race or variety (vyhadinaea) not found elsewhere. 
Our knowledge of the aquatic insects of Seistan is quite 
fragmentary, being based on a collection made in the middle of 
winter and only partially worked out. We obtained specimens of 
a considerable number of water-beetles, but have not succeeded in 
persuading any coleopterist to name them and our collection of 
Diptera met with more than one misfortune. The aquatic Rhynchota, 
as I have already pointed out, belong exclusively to the families 
Corixidae and Notonectidae. The genera represented (Micronecta, 
Corixa, Microcorisa, Anisops and Notonecta) are cosmopolitan and 
most of the species are known to be Palaearctic. Howsmall our true 
knowledge about the range of the less conspicuous water-bugs really 
is, is, however, illustrated by the fact that one of the Seistan species 
is otherwise known only from an oasis in the Algerian desert. What 
Ihave said about the Rhynchota also applies to the Diptera. One 
species of Tipulid (Symplecta elongata) is recorded as Persian and 
one Ephydrid (Halmopota viridescens) has been described from 
Seistan as new; the other flies are well known European species. 
So probably is also the May-fly (Palingenia) abundant in its larva! 
state on the banks of the Randa stream. 
The aquatic fauna of Seistan is thus, as might be expected 
from its geographical habitat, mainly Palaearctic. Particularly in 
- the fish, it has affinities with that of the highlands of Central 
Asia, but the molluscs belong to the geographical association I 
have recently called the Afghan type—not true Eurasian but 
belonging to species with both Palaearctic and Oriental relation- 
ships. They have, indeed, been introduced, with part of the fish- 
fauna, into Seistan recently, from the lower mountainous districts 
of Afghanistan and Baluchistan. It is among the less highly 
organized invertebrates that the tropical Indian element is most 
clearly manifest, but although this element is apparently absent in 
the fish, it appears (to go beyond the groups discussed in this paper) 
among the birds, of which Mr. Stuart Baker writes:—‘“ The 
geographical affinities are Indo-Palaearctic, the races of resident 
birds nearly all belonging to the Palaearctic rather than to the 
Tndian forms sss On Sone other hand a few sub- “species, appat- 
ently resident, are typically tropical Indian.. : 
