Careful study of insular faunas, such as that of Madeira by T.
This view is supported by Neumayr's comparison of Jurassic faunas throughout the world.
In some cases, such as the Ethiopian and Neotropical and the Palaearctic and Nearctic regions, the faunas, although distinct, are related, several forms on opposite sides of the Atlantic being analogous, e.g.
Where two of the faunal realms meet there is usually, though not always, a mixing of faunas.
Oceanic islands have, as a rule, distinctive faunas and floras which resemble, but are not identical with, those of other islands in similar positions.