304 



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



Ekman's table with some additions from Brandt's table, from Remane 

 (1940), and new additions (marked by asterisks in Table 126) according to 

 S. Sagerstrale (1957). 



30-35 25-30 



Fig. 145a. Alteration of salinity from the passage from the North Sea far into the 

 Baltic. A Surface salinity in February ; В Change of salinity along the vertical cross 

 section in August (Remane and Wattenberg). Numbers of animal species are 



encircled in A. 



There is an excellent summary of present knowledge concerning the distri- 

 bution of Baltic Sea fauna in the works of the Finnish investigators J. Vali- 

 kangas (1933) and S. Sagerstrale (1957), and the Swedish zoologist Ekman 

 (1933 and 1935). 



Propagation to the east. The most common Baltic hydroids— Clava squamata, 

 Sertularia pumila, Obeliageniculata and Campanulariaflexuosa—are character- 

 istic only of the western part of the Sea. Of the two Medusa known to exist in 



