Three different extraction methods for Turbellaria were compared, 2 of which use living material. The first method is based on sea-water ice treatment (Uhlig-method), the second employs decantation of narcotized fauna (MgC1,-method). The third method is the Bamett-method, performed on preserved material. Three series of 12 samples each were analysed quantitatively. Turbellaria were counted and identified to the order level. For the turbellarian population, as a whole, the numbers of individuals extracted alive (Uhlig-or MgC1,-method) was less than 50 % of the number extracted from the preserved samples (Barnett-method). Differences between Uhlig-method and MgC1,-method were not statistically significant. However, for Acoela and Retronectida, the Uhlig-method was more efficient than both other methods. We conclude that for a reliable quantitative analysis of Turbellaria 2 different extraction methods are required: one should employ extraction of living material (Uhligmethod) and one extraction of fixed material. For qualitative investigations extract~on of living material is recommended.

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The family Archimonocelididae Meixner, 1938 has been revised. The family contains two subfamilies, each comprising two genera: the Archimonocelidinae with Archimonocelis Meixner, 1938 and Meidiama Marcus, 1946, and the Calviriinae subfam. nov. with Asilomaria Karling, 1966 and Calviria gen. nov. with 20, 2, 1, and 3 species, respectively, 13 of which are new to science.

Recent data and opinions on meiofaunal ecology are briefly reviewed ; and from scattered data, the place of turbellarians in the meiobenthic community is discussed . Turbellarian diversity, density, and biomass are higher in sandy habitats than in muddy bottoms . In sand, turbellarian diversity is of the same magnitude as that of other important meiofaunal taxa, while densities range between 7-25% of the total meiofauna . Mean individual turbellarian dry weight seems to be four times that of nematodes and in sandy habitats turbellarian biomass may be equal to or excede that of nematodes. Most turbellarian species may be considered as predators and in this respect may take the place occupied by macrofaunal species in muddy sediments . mens .

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