sumption to the morphologist. The
apparent absence of Peripatus in Madagascar indicates that it did not
come from the east into Africa, that it was neither Afro-Indian, nor
Afro-Australian; nor can it have started in South America. We therefore
assume as its creative centre Australia or Malaya in the Cretaceous
epoch, whence its occurrence in Sumatra, Malay Peninsula, New Britain,
New Zealand and Australia is easily explained. Then extension across
Antarctica to Patagonia and Chile, whence it could spread into the rest
of South America as this became consolidated in early Tertiary times.
For getting to the Antilles and into Mexico it would have to wait until
the Miocene, but long before that time it could arrive in Africa, there
surviving as a Congolese and a Cape species. This story is unsupported
by a single fossil. Peripatus may have been "sub-universal" all over
greater Gondwana land in Carboniferous times, and then its absence from
Madagascar would be difficult to explain, but the migrations suggested
above amount to little considering that the distance from Tasmania to
South America could be covered in far less time than that represented by
the whole of the Eocene epoch alone.

There is yet another field, essentially the domain of geographical
distribution, the cultivation of which promises fair to throw much light
upon Nature's way of making species. This is the study of the organisms
with regard to their environment. Instead of revealing pedigrees or
of showing how and when the creatures got to a certain locality, it
investigates how they behaved to meet the ever changing conditions of
their habitats. There is a facies, characteristic of, and often peculiar
to, the fauna of tropical moist forests, another of deserts, of high
mountains, of underground life and so forth; these same facies are
stamped upon whole associations of animals and plants, although these
may be--and in widely separated countries generally are--drawn from
totally different families of their respective orders. It does not go to
the root of the matter to say that these facies have been brought about
by the extermination of all the others which did not happen to fit into
their particular environment. One might almost say that tropical moist
forests must have arboreal frogs and that these are made out of whatever
suitable material happened to be available; in Australia and South
America Hylidae, in Africa Ranidae, since there Hylas are absent. Th