FOSSIL REMAINS OF MAN 
INTRODUCTION. 
There can be no doubt, from a study of fossil skeletons, that at 
the remote geological period when back-boned animals first 
appeared as dwellers on the land, their blood was no warmer than 
the air around them. None of these animals, in fact, ranked 
higher in the scale of life than the cold-blooded reptiles of the 
present day ; but they soon spread widely and became suited to 
every sphere of existence, not only occupying the various parts of 
the land itself, but also invading the air as flyers, and even 
returning to the sea as swimmers. They exhibited unparalleled 
diversity, many of them were of bizarre shape, and some attained 
a size which has uever been equalled among land-animals in 
later times. 
During the whole of the " Age of Eeptiles," however, these 
different adaptations and remarkable growths occurred without 
any increase in the relative size of the brain. It was not until 
the appearance of warm-blooded quadrupeds, or mammals, towards 
the end of this age, that increase of brain-power became the 
essential factor of success in the struggle for existence. The day 
of mere bodily bulk and listless response to surroundings was now 
over ; and the place of the reptiles was taken by animals in which 
the enlargement arid increased efficiency of the brain were 
obviously of prime importance. As time passed, only those 
mammals survived and flourished, in which advances in the 
efficiency of the brain kept pace with increase in size or with 
special changes in the rest of their body. The lower races only 
continued to live when they were removed from stress of com- 
petition on such isolated lands as Australia, or when they were 
.represented solely by small forms, which needed little food, and 
readily found safe shelter from their enemies. 
There are several reasons for supposing that the earliest 
ancestors of all the mammals, with this remarkable tendency to 
enlargement and complication of the brain, were little tree- 
