In two previous papers I have set out the conclusions generally held by Northern geologists in regard to the more recent history of the Eastern Baltic, according to which it was once a great enclosed fresh-water lake or sea, the Ancylus lake, which by the breach in the land-bridge connecting Skäne and Denmark was converted into a brackish-water sea, the Litorina sea, which has in turn become less and less saline until it has reached its present condition.