In the past half century much efforts have been made to establish the exact publication dates of several important books, serials, and other issues. An admirable attempt towards assembling these data is the ”Journal of the Society for the Bibliography of Natural History” of which 13 parts have appeared (1936-43). A disadvantage of this journal to the botanist is that it has many pages devoted to zoological publications. Besides, it is exceedingly expensive. Many data are found in the Journal of Botany, the Kew Bulletin and the Journal of the Arnold Arboretum mainly composed by Barnhart, Britten, Fernald, Jackson, Marshall, Merrill, Kuntze, Sherborn, Sprague, Stearn, Wiltshear, Woodward.