The present paper contains descriptions of several new species of the genus Bactra Stephens from the tropics of the Old and New World, while stray notes and noteworthy records on known species are added. Records on Australian species are excluded, pending an opportunity for a revision of the entire Bactra fauna of that continent — with the exception of two species which are recorded in order to rectify some synonymies. In total one allied genus, ten species, three subspecies and one forma are described as new, while records on 42 already known species are presented. Since the genital characters of Bactra species are of such paramount importance it was deemed necessary to present elaborate figures of the genitalia of the two sexes, besides the usual technically indispensable descriptions or redescriptions of the species. At the other hand photographic illustrations of the entire insects usually are disappointing, the markings being very much the same. Therefore I abstained from including such photographs, with one exception : that of the type species of the new genus, Protobactra diachorda (Meyrick). In the Palaearctic and Aethiopian regions the character of speciation in the three principal subgenera of Bactra, viz. Bactra, Chiloides Butler and Nannobactra Diakonoff, is quite different, as has already been elaborated in my previous reviews of the genus. The South American fauna follows basically the same pattern. The species of the subgenus Bactra, however, are more differentiated than their relatives of the Old World and are therefore easier to discriminate. The subgenus Chiloides is equally rich in well-defined species in South America as it is in Asia and Africa. Finally, subgenus Nannobactra appears to be enigmatic all over the world (with the exception