356 



BIOLOGY OF THE SEAS OF THE U.S.S.R. 



sulphide, while a new flourishing development of an original fauna took place 

 in the new environment. 



Mae otic basin 



The fauna of the new Maeotic basin (Fig. 173) — its deposits occurring between 

 the Sarmatian and the Pliocene — owing to the establishment of a link with the 



Fig. 173. Maeotic basin (Kolesnikov). 



ocean again received a number of typical Mediterranean forms alien to the 

 Sarmatian period (Ostrea, Venerupis, Lucina, Dosinia, Cerithium, Area), 

 retaining only a few of the Sarmatian ones. The composition of the fauna in 

 the upper deposits of the Maeotic basin changed sharply again and, dis- 

 placing the Mediterranean forms, species of the genus Congeria and the 

 gastropods Neritina, Hydrobia and Micromelania appeared. 



The process of loss of salinity in the Maeotic basin in the vicinity of the 

 Kerch peninsula is well illustrated by Andrussov's table (1926) of the number 

 of species in the three overlapping layers of deposits {Table 140). 



Archangelsky thinks that the hydrological conditions of the eastern part 

 of the Maeotic Sea were very similar to those existing at present in the Black 

 Sea and that there was a deep part which was contaminated by hydrogen 

 sulphide. 



Pontic Lake-Sea 



The so-called Pontic Lake-Sea was formed during the Pliocene Period (Fig. 

 174), its fauna differing greatly from those of the Sarmatian and Mediter- 

 ranean. The huge inland brackish-water lake-sea (similar to the present-day 



