With 'Biogeography and Ecology in South America' as the general theme, a total of twenty-nine contributions by thirty authors is offered here in two volumes, being volumes 18 and 19 of the Monographiae Biologicae. Most of these discussions deal with decidedly specialist themes and the editors have been particularly concerned to ensure that the authors enjoyed the greatest possible freedom in the preparation of their work in order that different points of view and interpretations, together with some questions of controversy, may be clarified. This also applies, of course, to the several chapters in which general themes (geographical substance, climate, geology, vegetation, amongst others) are discussed. Since the amount of material available is too great to enable one to aspire to a presentation of the complete biogeographical and ecological picture, this procedure seems expedient. However, these two volumes could well be regarded as being a preparatory work for just such a complete description. Each of the separate technical contributions refers to the continent as a whole, in order to characterise it as such from the viewpoint of the specialist. For this reason it was necessary to forgo special discussions of particular regions or types of landscape, although South America of all places is remarkably rich in unique regional phenom ena, the altiplano of Peru and Bolivia, the relict forests of Fray Jorge, the shrub formations of Tierra del Fuego, the lakes of the High Andes, for example.