It is an incontrovertible fact that a large number of elements of the fauna of southern Chile show no phylogenetic relationship with the rest of the American fauna, but are related to groups in New Zealand, Tasmania, Australia, New Guinea, South Africa and subant-arctic islands. It is equally certain that all the higher systematic categories of animals which have elements adapted to cold climates in the southern hemisphere possess a discontinuous geographical distribution such as those mentioned above. On the other hand, the nature of the vast majority of animals distributed over widely separated areas is such that transport either active or passive across now existing geographical barriers and under present climatic conditions would be extremely improbable. It is particularly significant that the majority of phytophagous insects showing a discontinuous distribution in cold-temperate regions of southern hemisphere still nourish themselves today, exclusively or by preference, on lower vascular plants (ferns) or gymnosperms (conifers). All these insects may be classed as primitive because of coincidence of their morphological characters with their relict distributions. In so far as phytophagous insects on specific host plants are concerned, it is difficult to explain their present geographical distribution without postulating that Antarctica has been the most important centre of dispersion of flora and fauna, especially during the Cretaceous, of all the cold-temperate regions of the southern hemisphere.