This title is monograph 16 of the Flora Neotropica series. Farr's treatment of slime molds includes 280 species found in the Neotropics. Discussions of the morphology of plasmodium and sporophore and of the collection, care, and preservation of specimens are also included. The aim of this work is to provide a monographic treatment of the Myxomycetes known to occur in those countries and islands that lie partly or wholly between the Tropics of Cancer and Capricorn. About 280 species are known from this geographic range which, of course, comprises a great variety of environments ranging from tropical to alpine.