The Foraminifera of two submarine cores from the basin of the western North Atlantic have been examined. Vertical faunal variations suggest two sub-Arctic faunas separated by a warm-temperature fauna, and these are beneath the present warm-temperate fauna. The Arctic faunas are interpreted as representing the two latesst ubstages of the Wisconsin. A post-Wisconsin fauna in one core suggests warmer surface waters than at present.
Continuous sampling and quantitative study of the faunas are the most feasible methods for study of core faunas. A method of studying sizes of Foraminifera is described, and a possible correlation between sizes and ecologic factors is indicated.