INTRODUCTION. xlv 
analogues to the Amphitheres and Phascolotheres of our 
oolitic strata. 
If ever the first types of the primary groups of the class 
Mammalia radiated from a common centre, it must have 
been at a period incalceulably remote, and there is small 
hope of our ever being able to determine its site, by reason 
of the enormous alternations of land and sea that have come 
to pass since the class was first introduced into our 
planet. We find, however, that, from the period when 
the great masses of dry land assumed the general form 
and position that they now present, the same peculiar 
forms of Mammalia characterized their respective Faunz : 
and the evidence of the distribution of the recent and 
extinct pliocene Mammalia favours the conclusion that New 
Zealand, Australia, South America, and the Old World 
of the geographers had been as many distinct centres of 
creation. 
By the same evidence we are compelled to admit, that 
the difficulties which beset the Linnean view of the actual 
diffusion of organized beings * are insurmountable. Ac- 
cording to the hypothesis that all existing land animals 
radiated from a common Asiatic centre within the historical 
period, we must be prepared to believe that the nocturnal 
Apteryx, which is neither organized for flying nor swim- 
ming, migrated across wide seas, and found its sole resting- 
place in the Island of New Zealand, where alone the re- 
mains of similar wingless birds have been found fossil : 
—that the Wombats, Dasyures, and Kangaroos as exclu- 
sively travelled to Australia, where only have been found, 
in pliocene strata and bone caves, the remains of extinct 
* See Linnzeus’ preface to the ‘ Museum Regis Adolphi Frederici,’ 1754: and 
the excellent remarks in Dr. Pritchard’s ‘ Physical History of Man,’ vol. i. 1826, 
pp. 16, 81. 
