Foxworthy and Symington published revisions of the dipterocarp family for the Philippines (11 genera, 52 species) and Malaya (14 genera, 168 species) in 1938 and 1943 respectively. From 1926 till 1961 van Slooten published revisions of several genera for Indonesia, but knowledge of the largest genera, Shorea and Hopea, and of the island with the greatest number of species, Borneo, remained defective. Plans were developed by the Forestry Departments of Sarawak, Brunei, and Sabah, to fill the gap in a coordinated effort, of which this book is the first substantial result. A first precursory paper with new species appeared in Gard. Bull. Sing. 19 (1962) 253—319, a second, with taxonomic and nomenclatural discussion in vol. 20 (1963) 229—284. A Manual for Sabah, by W. Meijer, is in the press, one for Sarawak, also by Ashton, in preparation. When these are finished, the 72 species listed by Symington for Sumatra are still to be investigated, as well as the rich materials collected by Kostermans in Indonesian Borneo; then a comprehensive revision for the whole of Malesia can be written. This book means one more step towards the clearing up of the difficult tribe of the Shoreeae. The author suggests that eventually all genera save Parashorea thereof may be merged to one, objecting against elevation of the present sections in Shorea to the rank of genus. In this book are recognized Upuna (1 sp.), Anisoptera (4 spp.), Dipterocarpus (22 spp.), Dryobalanops (4 spp.), Cotylelobium (3 spp.), Vatica (19 spp.), Parashorea (4 spp.), Hopea (19 spp.), Shorea (73 spp.); this makes for Brunei 151 species, 41 of which were described after 1957. Shorea trees seldom produce the flowers on which the taxonomic subdivision is based, and foresters have developed a (largely concurrent) subdivision into Field Groups, based on bark (recently studied by Whitmore), slash, stipules, and other vegetative characters.