APPARENTLY CORRELATED TO THE CONDITIONS OF LIFE. 
299 
respectively Shumish Kul, Jaksi Klich, and Jamati Klich. When tlie level of the 
sea was changed these three depressions remained, for a time, as isolated lakes, 
each containing a separate sample of the fauna of the sea living in it. The lakes 
gradually dried up, becoming salter and salter; and it is the object of the present 
paper to investigate the changes which befell the animals inhabiting them during this 
process. 
General Account of the Desiccation of the Aral Sea. 
Before entering- into a detailed account of these lakes, it may be well to describe 
briefly the present conditions of the Aral Sea itself, of which they once formed a part. 
As is well known, the Aral Sea is a closed basin, receiving the waters of two rivers 
only, the Syr Darya and the Amu Darya. In this respect, it resembles the Caspian 
Sea, which receives the Volga, Ural, and Emba rivers. It is universally supposed that 
these two seas were united at a comparatively recent period. The evidence for this 
belief is the statement that banks of shells of species now living in the Caspian Sea 
are found on the land lying between them. As the level of the Caspian Sea is now 84 
feet below that of the Black Sea, and tiie level of the Aral Sea is 128 feet above that 
of the Black Sea, if it be supposed that the respective levels of the beds of these two 
seas were formerly the same as they are now, it follows that the Caspian Sea must, at 
the time of its connection with the Aral Sea, have been more than 200 feet deeper 
than it now is. On the other hand, the change in the levels of the two seas may have 
been due to subsidence of the bottom of the one, elevation of the other, or both. It is 
further supposed by many that the conjoined Aralo-Caspian Sea had a northward 
extension, probably on the east of the Ural range, thus connecting with the Arctic 
Ocean. One reason for this belief, amongst others, is the presence of a Seal in the 
Caspian Sea whose affliiities are rather with Phoca vitulina of the Arctic Ocean than 
with P. foetida of the Mediterranean. It has also been supposed that this Aralo- 
Caspian Sea had an eastward extension as far as Lake Balkhash. The reason for this 
view is not easy to suggest, as none of the typical Aral fauna occur in Balkhash, nor 
are any deposits of Aralian shells found between the two waters. It may be added 
that Balkhash is bounded, both north and west, by very considerable hills, the 
Koi Djarlegan,’&c. 
Moreover, apart from the question as to the extent of the hypothetical Aralo- 
Caspian Sea, it has been suggested that the Aral Sea, at all events, has retired in recent 
times from some considerable area, and is continuing to recede thus. This statement, 
which occurs in several text-books, would appear to be only partially supported by the 
facts which came within my own observations. In the summer and autumn of 1886, 
I visited the whole north shore of the Aral Sea lying between Gulf Peroffsky and 
the mouth of the Syr Darya. From Togusken to Sary Cheganak the shore is formed 
by high cliffs comjiosed of horizontal beds of Eocene formation, containing fossils. Of 
these I collected some 130 species, which have been examined by Mr. T. Roberts, of St. 
2 Q 2 
