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the pools around San Francisco Bay, with a view to anticipating events in the slower concentration of the Salton, which has now reached a stage of slightly more than one per cent, brine. It is eloquent of the arid conditions of the Cahuilla that the sink, or the region formerly occupied by Blake Sea, with an area of over two thousand square miles, bears only 8 species of trees, 33 shrubs and woody plants, and 81 herbs, or a total of 122 species, about the number that might be expected in a square mile in the Mississippi Valley, or on the eastern sea-board. Small as this number may be, the stage seems to be set for the appearance of new ones, as evidenced by the number of endemic forms. Striplex Saltonensis, Sphæralcea orcuttii, Cryptanthe costata, Astragalus limatus, A. aridus and Clæmæsyce Saltonensis occur so far as known in this sink, which must have been occupied by Blake Sea within four or five centuries. That they have ever lived elsewhere or before this can not be demonstrated, and their occurrence suggests most strongly a recent localized origination. The modifications in Aster exilis, Prosopis glandulosa, Striplex canescens, and Seirpua paludosus shown by individuals on emerged