Since the last serial paper on Strychnos appeared in print in 1965 in the Memoirs of The New York Botanical Garden, the authors have examined 1124 new collections, mostly from the senior author's two extended trips to various herbaria in Brazil which is especially rich in species of Strychnos. Among the several extensions of knowledge resulting from examinations of these specimens are the following: substantial progress on the classification of the S. mitscherlichii-complex; and two new species of Strychnos reported o be used in the preparation of curare (bringing the list to 19 species total). Includes keys, descriptions, and black and white illustrations. / Supplementary Notes on the American Species of Strychnos. IX. Since supplementary note VIII, the senior author has visited fourteen European herbaria, six of which had not previously been consulted for specimens of Strychnos. No new species or varieties are described as a result of these examinations, and no changes in nomenclature are proposed.