1g2I.| N. ANNANDALE: Fauna of Seistan. 247 
in the fauna. The bivalve, indeed, Lameliidens marginalis rhadt- 
naeus, is only a local race of one of the commonest Indian species. 
The scarcity of endemic species of molluscs of Seistan is 
noteworthy as providing additional evidence for the recent origin 
of the fauna. Only two species apparently belong to this category, 
namely Amnzicola sistanica and Vivipara helmandica. 
The aquatic molluscs, therefore, are of more mixed origin than 
the fish, probably having had better opportunities for immigration, 
and include a much more distinct Indian element. They pro- 
vide less evidence, moreover, of derivation from a high mountain 
fauna. 
The only Decapod crustacean found in Seistan is a race of a 
species widely distributed in south-western Asia and clearly of 
western rather than eastern origin. The race is not.known from 
higher altitudes than about 6,000 feet, but is cominon in the Quetta 
district of Baluchistan and extends its range southwards and 
eastwards from Seistan to the Punjab Salt Range. The absence of 
Caridea from the fauna of Seistan, and also of aquatic Isopoda, is 
noteworthy, but is easily explicable on geographical grounds. That 
of Amphipoda I have already discussed The Entomostraca have 
little geographical significance. 
The only leech discovered in Seistan (Liamnatis nilotica) is 
distinctly south-eastern Palaearctic in range. It is common in 
Egypt, and in many parts of the Mediterranean basin, but is not 
known from within the limits of the Indian Empire except in the 
extreme west of British Baluchistan. The aquatic Oligochaeta are 
essentially Northern Indian. ‘Two of the three species recorded are 
known only from India proper, while the third form is an Indian 
race of a cosmopolitan species. 
Four species of Polyzoa have been found in Seistan, Two 
of these, both species of Plumatella, are apparently endemic. One of 
these [P. (Hyalinella) higemmis| belongs to a cosmopolitan subgenus, 
the other [P. (Afrindella) persica] to one of tropical range and strictly 
Oriental so far as Asia is concerned. Of the other two represen- 
tatives of the group, one ( Fredericella sultana jordanica ) is a race 
of a cosmopolitan species, formerly known only from Palestine 
and the Volga system, while the other is identical with the Indian 
race of a species (Lophopodella cartert ’ known from India, China 
and Japan, but represented in the two last countries by a distinct 
race (davenportt). 
The only Coelenterate collected is a cosmopolitan species (Hydra 
vulgaris) common in the plains of India. 
Three species of sponge were found, viz. Spongilla alba, S. 
cartert and Ephydatia fluviatilis. The ‘last is a cosmopolitan 
species common in most parts of the Holarctic Zone but represented 
by distinct races in the Himalayas and Upper Burma and replaced 
in Peninsular India by an allied species (EH. meyent). S. cartert 
is the commonest of the Indian freshwater sponges and has also 
been taken in Hungary, Mauritius and the Malay Archipelago. 
S. alba is known from Egypt and from India, where it is usually 
