I have written this book because there is, as in almost all supraspecific ciliate taxa, an ur- gent need for an up-to-date revision of the oxytrichids, which are common in terrestrial, limnetic, and marine biotopes. The last comprehensive, illustrated guides to this group of hypotrichs were provided by KAHL (1932) and SmLER (1974b); however, as regards syn- onymy and faunistics, these works are outdated and not as detailed as EHRENBERG'S out- standing book from 1838. In KAHL's revision, the oxytrichids sensu stricto are described on about 30 pages, whereas in the present book the systematic section comprises about 830 pages. This extraordinary increase in page number is mainly due to the following points: (i) Species number increased from about SO in KAHL to about 170 in the present book. (ii) KAHL usually provided only a single illustration of each species, whereas almost all published illustrations on oxytrichid ciliates are included in my book. (iii) Modern, phylogenetic systematics of oxytrichids without morphogenetic data is impossible; conse- quentlY,*almost all detailed descriptions, usually dealing with the type species, have been included.(iv) Synonymy is discussed, and not only mentioned, as is unfortunately usual.
