Madagascar and new Caledonia. A problem in plant geography

The first result of this survey of the wide genera which have endemic species in New Caledonia is certainly to confirm the impression that there is indeed a noteworthy geographical association between Madagascar and that island, even if it is only a particular aspect of a more general relationship between Madagascar and Australasia as a whole. But the survey gives prominence also to another point, namely the unexpectedly small part that tropical Africa plays in the distribution of the genera reviewed. It almost seems as if there is some factor of exclusion affecting that great region, and there is no indication of any corresponding degree of relation between tropical Africa and New Caledonia such as has been detected between the latter and Madagascar.