Taxonomists working with material collected by the Sarawak Forest Department have often been hard put to decide how to quote numbers. Is the departmental series number preceeded by a letter S, or an F, or would it be best to quote only the collector and the number? I have tried to unravel the history of the Sarawak Forest Department herbarium number series in order to provide a guide to unequivocal citation. This has not been easy, as all collecting books previous to 1951 have disappeared, apparently during the second world war; many of the herbarium collections are now missing at Kuching and Kepong, where most were distributed, for the same reasons, though there seem also to have been large gaps in the series where numbers were never used. What has eventually been brought to light has been a masterpiece of confusion only vied with in complexity by its Sarawakian forbear, the remarkable numbering, or rather lettering, system of Haviland (explained in Kew Bull. 1907, 197— 198).