EXTENT OF THE FORMER ARALO-CASPIAN SEA. 
297 
and with them Buccinum dissitum, Mactra ponderosa (Eichw.), two species of Turbo , 
and some minute marine univalves. 
Upon the whole, the aspect of these shells conveyed to us the idea that they are 
not of remote age, and probably upper miocene ; but being all of marine or oceanic 
origin, and not approaching very nearly to existing forms, they are clearly to be 
distinguished from those remains which occur in the higher limestone of the 
adjacent hilly steppe. To this deposit, which borders the Sea of Azof and Black 
Sea, and extends over a prodigiously large region upon the east, we now beg spe- 
cially to direct the attention of our readers. 
Hi, Aralo-Caspian or Steppe Limestone— the Relic of a great former Eastern Me- 
diterranean.— The tertiary strata we have been considering, whether of Eocene 
and Miocene age, or passing from the latter into Pliocene, are to be viewed 
on the whole as widely spread marine formations which have been accumulated 
in true oceanic seas or their estuaries. The formation we have now to con- 
template is strikingly dissimilar, in offering throughout one of the largest basins 
in the world, an uniformity of peculiar characters which separates it decisively 
from any tertiary deposits of Western Europe. This peculiarity consists in the 
imbedded fossils being analogous and to a great extent identical with those of the 
present Caspian Sea, in which the univalves (with the exception of one doubtful 
species of Rissoa ) are of freshwater origin, associated with forms of Cardiacete and 
Mytili which are common to partially saline or brackish -waters. 
This distinguishing feature, then, of the present Caspian prevails throughout all 
the enormously developed tertiary formations of the southern and south-eastern 
steppes (European and Asiatic), and leads at once to the conviction, that during 
long periods antecedent, as will be hereafter explained, to the historic era, a va* 
region of Europe and Asia was covered by a Mediterranean Sea o rac is wa er 
of which the present Caspian is the diminished type. (See Nos. 10 an o ap 
To render the distinction between these accumulations and all others cleai am 
unambiguous, we have adopted the term Aralo-Caspian, ** a P^ma geogra- 
phical sense by our great precursor Humboldt, to this region of the globe. 
With the’ remoter limits of this former Mediterranean we are necessarily on- 
* tPfl Tndffine from the recital of travellers and from specimens of the 
acquainted. Judging and the Aral Sea; beyond 
rock, we have no doubt that it exieuueu , . , 
which the low level of the adjacent eastern deserts would lead ns to infer, that 
spread over wide tracts in Asia now inhabited by the Turkomans and Kirghis, and 
