JoHS. Schmidt 



187 



shape (see this Journal,Yo\. vii, 1918, Plate VII). This quite regular 

 gradation in the average number of vertebrae has now been found in all 

 Danish Qords where investigations have been undertaken and it must 

 therefore be considered a definitely established fact. 



Fig. 2. Ise Fjord — Roskilde Fjord area, Sealand, Denmark. 

 Showing the salinity of the water in per mille (°/oo) at the end of November, 1919. 



The chemical and physical conditions of our ^ords are not closely 

 investigated. Among the conditions which are best elucidated the 

 salinity of the water exhibits the most characteristic picture. As will 

 be seen from Fig. 2 this factor shows a gradation which accurately 



