Until recently relatively little attention has been paid to the study of chromosomes in liverworts. The first substantial contributions were made by Heitz (1927, 1928) and Lorbeer (1934). In the second half of this century chromosome studies on liverworts were mainly carried out in Europe (e.g. Fritsch 1972; Newton 1977, 1979) and Japan (e.g. Tatuno 1959; Segawa 1965a, b, c; Inoue 1968). Inoue (in Koponen 1979) reports that until now 28% of all bryophyte species in Japan have been investigated as to their chromosome complement. A comprehensive, but rather outdated, survey of chromosome numbers in Hepaticae and Anthocerotae was given by Berrie (1960). Work on a new, updated survey is now underway (Fritsch, in prep.). In the present article results are presented of a cytotaxonomic investigation of European species of the genera Aneura and Riccardia (Aneuraceae). Most specimens were gathered in the Netherlands, but some chromosome counts based on French and German plants are also included.