DRAFT UCiseeeweeman. ‘ in a massof water that can be recognized by its cheracteristic temperature and salinity relation, Water masses are named after oceanic regions where they are formed or are found. Further mixing between two or mcre water messes may occur. By comparing the horizontal continuity of water masscs present in the area studied, movement of watex into the area may be estimated, The water masses in the Pacific were named, described, and located on the basis of the relatively sperse data taken in this ccean before about 1940, Tience, the descriptions and boundaries are somevhat erbitrary, and the characteristics of* a water mass are accepted as varying within only moderately well defined limits. The boundary regions contain wseters of interuediete types. the water masses to be dealt with here are given below. Except for the last one listed, thexy ere found in tha upper layers, within the ceographical limits specified, (1) Pacific Equatorial Water, extending from abovt 2° S to 6° Nin these longituaes. (2) Western North Pecifiec Central Water, from 16¢° Ww to the western boundary of the ocean, and from abovt 2° N to Lo? N, (3) North Pacific Intermediate Water, occurring at depths from 400 to 1200 meters over most of the North Pacific. Te FF