512 Prof. K. A. von Zittel—On the Mammaiia. 
(and possibly also Asia), North America and Africa. Whether to 
this extensive zoo-geographical kingdom Australia also belonged at 
the same time, or whether, as has often been stated, the Mesozoic 
forms withdrew themselves there at a later period, cannot, for lack 
of the needful proofs, be determined with certainty. Under any 
circumstances the present Australian mammals must in this case 
have been very radically changed, and they now retain only a few 
features of their very ancient ancestors. 
From the Tertiary period onwards, the distribution of the land 
mammalia went forth from certainly not more than three areas 
of development, or so-called ‘centres of creation.’ 
J. The oldest, the earliest separated off from the rest, and still the 
mostly distinctly bounded of all the zoo-geographical kingdoms, 
is formed by Australia, with the neighbouring island of Tasmania. 
In spite of great diversity with regard to climate and meteorology, 
and in spite of striking differences in the conditions of food support, 
this kingdom contains the whole of the now existing Monotremata 
and Marsupials with the exception of the Didelphyidz, which live 
to-day in America and in the Tertiary period were also distributed 
over the whole northern hemisphere ; and beyond these only a few 
forms, probably imported from outside at a later period, such as 
Bats, Mice (Pseudomys, Hydromys, Acanthomys, Hapalotis, Kchiothria), 
and the Dingo, a variety of the domestic dog. According to A. R. 
Wallace,! Australia was already separated from the other continents 
at the close of the Mesozoic period; moreover, during a portion of 
Tertiary time it still included New Guinea, Celebes, the Solomon 
and perhaps also the Fiji islands, and possessed a considerable 
extension towards the South and West. Even to-day, Australian 
Marsupials are met with in New Guinea, Celebes, Amboyna, and 
even in Timor, mingled with Indian placental Mammals. Tor its 
connection at one time with South America, the abundant occurrence 
of fossil Marsupials in the Santa-Cruz beds of Patagonia is valid 
evidence. 
II. The second zoo-geographical kingdom, formerly not less 
sharply defined than the Australian, is South America or Austro- 
Columbia.” Up to the youngest Tertiary period this kingdom 
contained only Hdentates, Toxodontia, Typotheria, some very 
peculiarly differentiated Perissodactyla, Hystricomorphous Rodents, 
Platyrhine Apes, and Marsupials, which, however, very consider- 
ably differ from the Australian forms of this group. From this 
area of development, Africa received, probably at the beginning 
of the Tertiary period, some scattered wanderers, such as the fore- 
runners of Orycteropus and Manis, the Hyracoidea, which have 
perhaps descended from a common root with the Typotheria, and 
some Hystricomorphous Rodents. But the connection of the South 
American or Neo-Tropical kingdom with Australia and South Africa, 
which at one time existed, must certainly have been already again 
dissolved in the older Tertiary period, for the forms belonging to 
1 Wallace, A. R., The Geographical Distribution of Animals, 1876. 
2 Huxley Th. Proc. Zool. Suc. London, 1868, p. 316. 
