Engler (1893) was the first to recognize Tylecarpus as a distinct genus. Howard (1940) pointed out that Medusanthera was an older name for the genus and must replace the name Tylecarpus. The genus Medusanthera is closely related to Lasianthera, Gastrolepis, and Discophora in having, in common with those genera, polypetalous flowers, stamens with pubescent filaments, and a characteristically flattened drupe with a fleshy appendage borne laterally. Further study of this genus revealed that the species recently assigned to Medusanthera (Tylecarpus of Engler and Sleumer) represent more than one generic entity. Therefore, in this paper Tylecarpus Merrittii, Tylecarpus andamanicus, and Medusanthera australis are segregated into the new genera Codiocarpus and Irvingbaileya. The principal characters supporting this segregation are to be found in the structure of the fruit, especially in the form of the putamen, although secondary characters are found in other parts of the plant. Codiocarpus differs from the other genera mentioned above in that the staminal filaments are filiform and glabrous. The essential differences for generic segregation are summarized in the synoptic key which follows. I have not seen mature fruits of Lasiainthera or of Gastrolepis, and the descriptions of these in the literature are sketchy. For that reason I have avoided using fruit characters in the keys for these two genera. All other descriptions have been drawn up from examination of the cited material. No mature wood was available in existing collections of Irvingbaileya australis, Codiocarpus andamanicus, Lasia-nthera africana, and Gastrolepis austro-caledonica. The anatomical descriptions of wood structure of these species were drawn up after examination of twigs from herbarium sheets. Of these genera, one, Discophora, is found in the New World, occurring from Brazil to Colombia and Panama. Lasianthera is from tropical Africa. The others are from Australia, the Philippines, the East Indies, and Oceania. Their relationship is established from evidence found not only in the structure of the flowers, the fruits, and the similarity of appearance but also from similarities of wood structure and pollen-grain morphology.