Ever since the pioneer researches of Miss Polak on Malesian peat before the second world war, it has been clear that an immense amount of information of great botanical interest was waiting to be discovered in the peat, coal, clay and shale deposits, which are so widespread in the sedimentary record of this area. It was an economic motive which in 1953 led the Brunei Shell Petroleum Cy. in Brunei (NW. Borneo) to start palynological research. The aim was to distinguish palynological zones in the thick Tertiary oil bearing sediments which were difficult to correlate otherwise. During the course of this work many data of botanical interest came to light and short notes on these results have been published already.