president’s address. 
481 
the Baltic at the present day there is, in a sense, a blurring of 
the distinction between fresh and salt fauna, but so far as 
concerns the permanent additions to the fresh water fauna which 
we owe to its past history, they are but four at most — Mysis 
relicta, Chiridotea entomon, Pallasea quadrispinosa, and Ponto- 
poreia afftnis, and it is doubtful if even these all owe their 
acclimatisation to the freshening of this sea. The occurrence 
of C. entomon, for instance, in the Caspian Sea, with which 
the Baltic probably never had direct connection, as well as its 
habits of life, render such a conclusion very doubtful. 
The Caspian Sea is a relic of a great inland sea or series of 
seas extending in Miocene and Pliocene times from Vienna to 
the Sea of Aral, and almost isolated from the Mediterranean. 
The Sarmatian Sea of the Upper Miocene seems to have largely 
dried up in the West, but to have persisted and become 
fresher in its Eastern parts, the deposits of the Pontic period 
being those of fresh, or slightly brackish, water and extending 
over the basins of the Caspian and Aral Seas and the northern 
half of the Black Sea. 
The Caspian, Aral and Black Seas were united for a long 
time, and separated from the Mediterranean, and the union of 
the three was dissolved before, in postglacial times, the Black 
Sea and JEgean Sea became connected. Hence we find in the 
fauna of the Caspian and Aral Seas some relationship with the 
Black Sea, but scarcely a trace of Mediterranean influence. 
The Caspian Sea is a relic of the Pontic Sea, and its fauna is 
full of interest on this account. The Mollusca of it are regarded 
by Kobelt as all belonging to Sarmatian species. The genera 
Adacna and Monodacna, found also in the northern parts of the 
Black Sea, are relics of this period. The fishes also illustrate 
the past history, since they have a striking affinity to the fish 
fauna of the Danube, which, until the separation from the 
Black Sea, flowed into the combined Ponto-Aralo-Caspian 
basin. But perhaps the most striking feature of the fauna is 
the luxuriance of certain genera which, except in the Caspian 
Sea, possess but few species. So, for example, there is an 
extraordinary variety of species of Cardium, and the Crustacean 
