Annals of the Transvaal Museum. 
39 
widespreading forms as Nectophryne and the Apoda have not extended 
further southwards in Africa and why the Dendrobatidae have such a 
disconnected distribution. To explain the paucity in Madagascar of early 
African mammals, Tullberg (whose paper I have not actually seen) suggested 
that the east part of Africa, along with Madagascar, had been separated by 
an arm of sea from the main south-western African mass, and not until after 
the isolation of Madagascar (about late Oligocene) were the two portions of 
Africa united, at which time East Africa was probably united to South-West 
Asia by a continuous land-bridge along which the Proboscidea reached 
India. There is much to be said in favour of this view if we include in the 
eastern section of Eocene times the whole of Sclater’s Cape Province with 
Madagascar, as it well explains the distinctness of that Province and its 
fundamental relationships with Madagascar. In such case there may have 
been various transitory connections between the separated areas, some of 
which would be the means of introducing certain American types which 
were shortly afterwards isolated in Madagascar. 
In concluding this short paper, it must be admitted that the kind of 
evidence that is required to properly establish these hypotheses is altogether 
lacking, in the almost complete absence of fossil forms : nor do we possess 
the whole evidence of comparative anatomy, for our judgments of generic 
relationships are based upon the more easily ascertained and superficial 
characters, and the data for a genetic arrangement of the genera are still 
wanting. Mocquard points out that in the Arcifera, especially the Hylidae, 
there are two sections parallel to those of the Raninae, so that it is even 
possible, though I think not probable, that our whole classificatory 
arrangement will have to be altered accordingly. The available facts 
certainly show how unsatisfactory must be any rigid arrangement of the 
world’s surface into zoological regions, seeing that the fauna of any large 
area is a heterogeneous assembly of species which have varied origin and 
history. 
