A systematic account of the holothurians of the New Zealand region is given, together with diagnoses of orders, families, sub-families, genera and species. The report is based on a total of 970 specimens, which comprise 18 genera, including Mensamariella n.g., and 25 species, including Protankyra rigida, Chiridota alleni, Chiridota mortenseni, Neothyonidium armatum, and Trachythyone squamata, spp.nov. Genera and species known in the fauna, but not encountered during the course of the present study, are diagnosed, and their systematic positions and distribution patterns are briefly considered. The distribution of known holothurians within the New Zealand region is discussed, as also are the external relationships and ultimate derivation of the group. The taxonomic state of the Class as a whole is indicated, and comments are made on the reliability of systematic characters within each group, together with some suggestions for modification and possible improvement of the present-day situation
