484 
SCOTT'S LAST EXPEDITION 
evolution of types. These new forms spreading out from 
their points of origin had to find their way southward 
along the attenuated land areas of South America, Africa, 
and Australasia. Thus on account of their relative isola- 
tion these three southern continents became characterised 
by peculiar and in some cases comparatively primitive 
assemblages of animals. They became, as it were, behind 
the fashion. For instance, Australia to-day still has its 
marsupial population of kangaroos and such-like animals. 
In Europe marsupial types are only found as fossils, 
showing that they lived here millions of years ago in the 
Mesozoic ages of the earth's history, but have long since 
been exterminated and supplanted by newer types. 
On account of the inadequate nature of the fauna of 
large parts of the Southern Hemisphere, man has had to 
stock these lands with northern animals. 
Very few cases are known where land animals of a 
southern origin have advanced northwards. Whether this 
generalisation applies in the case of the marine benthos of 
the continental shelves presents an interesting field of 
inquiry. The collections brought home in recent years 
by the various Antarctic and other expeditions which have 
trawled in the Southern Hemisphere will, perhaps, make it 
possible to give some sort of answer to this question. 
