66 



THE HABITAT OF THE EURYPTERIDA 



case. The various realms may be secondarily grouped according to 

 occurrence, as marine and terrestrial. In this latter group, two fur- 

 ther subdivisions may be made according to mobility: the courant 

 and the static waters. I propose the term courant for all terrestrial 

 waters which are constantly moving in a given direction, as do the 

 rivers. The following table brings out these points; of which further 

 discussion will not be given in this paper. 



CLASSIFICATION OF AQUEOUS BIONOMIC REALMS ACCORDING TO 



SALINITY 2 



CLASSIFICATION 



SELECTED EXAMPLES 





Range in 

 Permille 



Marine 



Courant 



Static 



of Salinity 



Examples 



Per- 

 mille 



Examples 



Per- 

 mille 



Examples 



Per- 

 mille 



I. Fresh .... 



O . O-O . 2 







Amazon River 

 at Obidos 



Rhine at 

 Cologne 



0.037 



0.178 



Lake Erie 



0.134 



II. Subbrack- 

 ish 



0.2-1.0 







Vistula near 



Culm 

 Arkansas R. 



0.201 



0.794 



Laacher See 

 Humboldt 

 Lake 



0.218 

 0.928 



III. Brackish.. 



I.O-IO.O 



Baltic Sea 



7.80 



Salt River 

 Rio de los 

 Papagayos 



1-234 

 9.185 



Palic Lake 

 Lake Biljo 



2.215 

 8.800 



IV. Super- 

 brackish. 



IO.O-20.0 



Sea of Azov 

 Black Sea 



10.60 

 18.30 







Caspian Sea 

 (in 1878) 



12.940 



V. Subsaline . 



20.O-3O.O 



Arctic Ocean 

 Hudson Bay 



2S-5o 

 26.00 







Van Lake 



22.601 



VI. Saline.... 



VII. Super- 

 saline. . . 



30 . O-4O . O 

 4O.O-289 



plus 



Behring Sea 

 Atlantic Ocean 

 Red Sea 



30.30 



35-37 

 38.80 







Albert Lake 

 Tinetz Lake 



30.772 



289.000 



2 The examples and salinities in this table are taken from the tables compiled from various 

 sources by Professor Grabau, and given in the "Principles of Stratigraphy" (87). The classification, 

 is new. 



