Page:The Habitat of the Eurypterida.djvu/72

 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.