During the past ten or twelve years, there has developed an extensive interest from a number of points of view in the myristicaceous genus Virola and, to a somewhat lesser extent, in several smaller but closely allied genera: Cornpsoneura, Dialyanthera, Iryanthera, Osteophloeurn. This interest has ranged from newly expanded large-scale exploitation of several species of Virola for commercial wood in South America and the extraction of a fatty oil from the seeds of various species of Virola and Iryanthera to phytochemical and pharmacological research on a number of species as little known hallucinogenic snuffs or as potential new therapeutic agents. From botanical collecting in the past quarter century, it appears that perhaps the northwestern part of the Amazon basin - particularly the sector lying in Colombia and the Rio Negro of Brazil - may represent the region of greatest specific diversity of Virola and several allied genera. Some of the recent collections greatly amplify the known range of certain species. For this reason, the publication of these phytogeographical observations, even when the collections are not voucher specimens for ethnobotanical data, has seemed justified. The establishment also of vernacular names through the citation of collections which authenticate them has likewise appeared to be worthwhile.