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bulletin: museum of comparative zoology. 



Density, at the Temperature in Situ. — In a region where waters of 

 different temperatures and salinities meet, where local vertical circu- 

 lation is active, and where winter cooling and summer warming are 

 pronounced, the distribution of density in the upper layers must not 

 only be complex, but constantly changing at any given locality. And 

 Gulf waters are no exception to this rule, if small differences be con- 

 sidered. But in its main outlines the density of the Gulf is compara- 



FiG. 37. — Salinity on the bottom, July-August, 1914. 

 ;i; i = 33 %<, - ; M = 35 %o +. 



tively uniform in summer. In 1914 and 1915, as in previous years 

 (1914a, 1915), density, both on the surface and in the depths, was 

 higher in the eastern than in the western part of the Gulf. But local 

 differences were more pronounced in 1914, owing to the distribution 

 of salinity (p. 231). And the area of low surface density (below 

 1.023), noted over the Western Basin in 1912 and 1913 (1914a, 1915) 

 was much more extensive in 1914. In August, 1915, the surface 

 density of the Western Basin (Station 10307; 1.0233) was lower than 



