The "tracks" are lines connecting areas which contain many disjunct species in unrelated taxonomic groups. Note amphitropical connections and amphi-Atlantic ones. Croizat, L. 1952. Manual of Phytogeography. Junk, The Hague Croizat, L. 1958. Panbiogegoraphy. Caracas. Croizat, L. 1960. Principia Botanica. Caracas. Croizat, L. 1964. Space, Time, Form: The Biological Synthesis. Caracas.