[Proceedings of the symposium 'Molluscan Palaeontology' : 11th International Malacological Congress, Siena (Italy) 30th August - 5th September 1992 / A.W. Janssen and R. Janssen (editors)]: The main branch of Miocene Gyraulus (Gastropoda; Planorbidae) of Steinheim (southern Germany): a reconsideration of Mensink's data set

The data set of the so-called main branch of Miocene Gyraulus, collected and measured by Mensink, has been re-examined by means of multivariate methods. New information was obtained by presenting the percentage of specimens which have a keel on the second or third whorl in a bivariate way. In an earlier multivariate analysis Lindenberg & Mensink used only six characters, in the present paper an additional two characters have been used. However, as the number of characters is small, some of them have not been adequately measured, and because the identification of part of the specimens was questionable, the results may still be insufficient.