12 Records of the Indian Museum. [VoL. XVIII, 
the ‘‘Lybian’”’ division of the eocene, a stage widely developed 
throughout the Mediterranean countries, and intermediate in age 
between the ‘‘ Londinian’”’ and ‘“‘ Parisian”’ of North-Western 
Europe where it is missing. 
‘“'This species is very scantily represented in the pebbles 
under examination, which are crowded with an Alveolina that occurs 
in profusion in the Lybian limestones of India which, conse- 
quently, have frequently been referred to under the name of 
‘“ Alveolina limestones.” Carter (Journ. Bombay Br. Roy. As. 
Soc.,: Vol. V5 p:-234y ploat; tig. 16,9853); and sdArchiae mand 
Haime (Descr. an. foss. groupe numm. Inde., 1854, p. 348) have 
regarded this fossil as specifically identical with A. sphaeroidea, 
Iam. (An. sans vert., 1822, Vol. VII, p. 615), which abounds 
amongst the rocks of the same age in the Pyrenean region. 
“The Alveolina limestone, showing the same dark colour 
as the Seistan pebbles,’ occurs in great abundance in the neigh- 
bourhood of Koh-i-Malik-Siah.’’ 
From this it follows that the deposit of which the cliffs are a 
section must have completely filled up the basin in which it was 
formed, at any rate at the site of the cliffs, and had been covered 
by a layer of entirely different and more recent origin that con- 
stitutes the surface of the desert over a great area in Persia, 
Afghanistan and Baluchistan. 
The lack of animal remains in the clay of the cliffs at Lab-i- 
Baring is a very important difference between it and the deposit 
now being formed in the Hamun in their immediate vicinity. The 
freshwater shells found subfossil in many parts of Seistan are in a 
remarkably good state of preservation, while those of the indi- 
viduals that still live in the Hamun are so free from erosion that 
even in adult individuals of Lamellidens the larval shell of the 
glochidium can often still be distinguished. It is, therefore, very 
improbable that shells, if they had ever existed in the cliffs, would 
have been completely destroyed. The lake of which the cliffs 
represented the bottom can, indeed, hardly have had a molluscan 
fauna. In this respect it resembled most Persian lakes, and the 
reason of its barrenness was the same:—its water was too salt, 
or rather contained too large a proportion of deleterious ? salts in 
solution. The clay of the cliffs is consolidated with mineral salts 
and the little streams that arise in clay hills of exactly the same 
structure and run down through little gorges towards the lake 
contain water of such salinity that the salts crystallize out at their 
margin (postea, p. 15). 
Now, the waters of the Helmand are fresh and those of Seistan 
become saline when they absorb salts from the soil. This was 
brought home to us in a very striking manner at Lab-i-Baring. 
_ | These pebbles have probably been brought by occasional floods from hills 
lying a considerable distance to the west or north-west of the lake. 
? ‘The macroscopic fauna of the saline streams in the cliffs at Lab-i-Baring 
consists of a few small insects. 
