This sixth supplement to the original and invaluable Index Filicum continues the tradition of cross-referencing all basionyms to their new names. It covers the period from 1976 to 1990, a mere 15 years in the nearly 250 years that separate us from Linnaeus. Yet it contains 344 pages full of new species and new combinations (statistics on the numbers of each category are not provided). The dates for this volume are not very strict: important publications before 1976 that were not fully indexed in the previous volume have been incorporated in the main body, not in the Addenda, Corrigenda et Emendanda (ACE). Compare, for instance, the mere 16 new combinations in Sphaeropteris made by R.M. Tryon in 1970 listed in the previous Supplement with the nearly 100 listed here! For the first time in pteridological history, pteridologists now also have access to infraspecific names, and have less excuse to ignore some of them quietly. Whether this is an advantage remains to be seen. Records only go back to 1976 (although some older infraspecific names are listed in the ACE), which means that lots and lots of older names (and all their corresponding autonyms) are still waiting to take up their proper place in the priority. With nomenclatural rules on infraspecific names as intricate as they are now, and without the excuse of ignorance, it is very temping to move away from the use of infraspecific categories altogether.