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The floral composition of living calcareous nannoplankton collected from surface waters near the Subtropical Convergence (STC), offshore south-eastern Tasmania, in January 1994 is presented. Emiliania huxleyi represented more than 90% of all coccolithophorids. Scanning electron microscopy showed a substantial increase in intraspecific variation of E. huxleyi, and in variation in coccolith size of Calcidiscus leptoporus, E. huxleyi type A and C. leptoporus (small), north of the STC. It is postulated that the percentage abundance of these taxa may be used to determine the position andlor shift of the STC zone through time, and therefore may be of use for palaeoceanographic studies.

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A diatom biostratigraphic study of the Maruyama Formation in the Makarov and Dolinsk areas of the southern part of Sakhalin Island indicates that its geologic time span ranges from ca. 14 Ma to 3.5 Ma or possibly younger, which is much longer than previous estimates (e.g. 9.5-5.3 Ma by Ingle, 1992). A middle Miocene age of the Kurasi Formation in the Makarov area is also given on the basis of diatoms. These results are presented with correlation to the Neogene sections in the Tenpoku area, northern Hokkaido. The diatom zones of Akiba (1986) and Yanagisawa and Akiba (1998) recognized in the Makarov area include the Denticulopsis simonsenii Subzone of the D. hyalina Zone (NPD4Bb ; middle middle Miocene, 14.6/14.5-13.1 Ma) in the Kurasi Formation and the 1st Member of the lower part of the Maruyama Formation, and the D. praedimorpha Zone (NPD5B ; upper middle Miocene, 12.9-11.5 Ma) in the 2nd Member of the lower part of the Maruyama Formation. In the middle part of the Maruyama Formation in the Dolinsk area, the type area for the formation, numerous specimens of reworked diatoms were observed. The