Citrus macroptera Montr. (family Rutaceae) is a small rain-forest tree occurring in New Guinea. Fractionation of the crude bark alkaloids, isolated in approximately 0.02% yield, has given an alkaloid, m.p. 140-141°, [α]~ -15' in chloroform, which has been shown by spectroscopic evidence to be (1). The structure of the alkaloid has been confirmed by its identification with the product obtained from reaction of the methiodide of platydesmine (2) with alkali.1 The alkaloid edulinine,2,3 isolated from Casimiroa edulis (family Rutaceae), has also been shown to be (1), but as the optical rotation of edulinine does not appear to have been recorded, it is not known whether the alkaloid now isolated from Citrus macroptera is edulinine or its optical enantiomer. Apart from this uncertainty, the n.m.r, data and other physical constants determined for edulinine and the C. macroptera alkaloid are in close agreement.The alkaloid (1) seems to be the first isolation from a Citrus species of an alkaloid closely related to the quinolone and acridone alkaloids which are typical of many other genera of the Rutaceae.4Since submission of this Communication, the isolation of edulinine from Eriostemon tmchyphyllus (Rutaceae) has been recorded.5