21. The genus Cercyon Leach (Coleoptera: Hydrophilidae). The author has revised the genus Cercyon Leach. All the species are keyed and notes on their ecology and distribution are given. Wollastons "littorale Gyll." is arenarius Rey and lugubris Oliv. is reported as new for the islands. 22. The genus Pachysternum Motschulsky (Coleoptera: Hydrophilidae). The genus and the species (P. capense Muls.) are new for the islands. They are described and notes on ecology and distribution given.