INTRODUCTION THE land faunas of oceanic islands have always excited considerable evolutionary speculation, and, starting with the “Origin of Species”, the Geospizinae, the endemic Galapagos finches, have probably featured in as many evolutionary discussions as any group of animals. They differ from almost all other land birds of oceanic islands in that there is more than one species on each island. Further, some of the species seem to grade into each other, and others are linked by freak specimens. Some workers have supposed that some quite peculiar method of evolution must have been involved.