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MR. W, BATESON ON SOME VARIATIONS OF CARDIUM EDULE 
John’s College, and Mr. Keeping, who state them to be of about the age of the London 
Clay and of the Bracklesham beds of England. In some places these cliffs rise from 
the water’s edge, and in others recede from it, opening up considerable valleys which 
slope gradually down to the shore. In places where the cliffs do not abut on to the 
water there is generally a sandy beach, but occasionally, as at Kukturnak, there is a 
steep bank of large shingle and pebbles. The shores of the Sary Cheganak (Yellow 
Gulf), which forms the northern limit of the Aral Sea, are low lying and sandy. These 
sands extend northward and eastward for about 150 miles, constituting the Kara Kum 
(Black Sand). The southern edge of the Kara Kum is thus the northern shore of the 
Aral Sea, and it is generally assumed that it was covered by those waters at a 
comparatively recent period. 
The waters of the Aral Sea oscillate greatly under the pressure of the wind, and 
this effect is especially seen when the wind is from the south for some days. The 
wmter is then driven in some hundreds of feet over the almost horizontal beach of the 
Sary Cheganak. 
The Mollusca which have been recorded as occurring in the Aral Sea are Cardium 
edide, Adacna vitrea, Dreissena jjolymorpha, Neritina Jiuviatilis, Hydrohia ulvw. 
In addition to these I found Hydrobia spica in largo quantities (this species is 
already knoAvn from the Caspian Sea) and also Neritina {1 n. sp.). 
The Cardium occurs in great numbers on all parts of the shore which I visited, and 
when the wind falls and the sea retires the shore is left covered with stranded Cockles. 
The highest limit to which the hood thus induced ever reaches is in this way more or 
less clearly shown by the fresh shells and other-dehris left behind. Above the level 
of this fresh deposit the ground is always strewn with old shells, indicating the area 
covered in past times by the water. The coast of the south-west shore of the 
peninsula Kukturnak is covered entmely with Cockle shells, extending in a band 
nearly a mile wide. With the exception of those points in wdiich the cliff rises from 
tlie water’s edge, there is always a tract of shore on which shells are found. On the 
hypothesis that the Aral Sea formerly had a much greater depth than at present, it 
would be expected that shells would be thus found in position for a considerable 
height above the present level, but this is not the case. On the contrary, where the 
shores are more or less steep the shells are found in great quantities up to a certain 
level, about 15 feet above the water, and above this level they are never found. In 
places where the land slopes very gradually to the water level the horizontal extent 
of the shelhcorered tract is very great, being as much as 15 miles in some places; 
but whenever the ground rises suddenly so as to reach a greater height than about 
15 feet above the Aral Sea level no more shells are found. The fact that the sheds 
cease abruptly at a definite horizon is true both in sandy parts of the coast and on the 
clayey tracts, and it is equally true of those deposits of shells which occur in the 
bottom of valleys opening to the sea which are now altogether dry, but which were 
formerly filled by the sea. Some of these deposits of shells reach inland four or five 
