Ancestors 15 
ably at least an indirect descendant of the Phororhacos. 
The Seriema defies exact classification, sharing characters 
of cranes, bustards, and eagles. Its beak and inner 
claw are like those of a bird of prey, while in form of 
body, and in the other claws of the toes, and in the legs 
it is crane-like. One of these birds which I have ob- 
served for years in captivity is as gentle and as fearless 
as a bird can be. It will chase insects and _field-mice 
outdoors in the Zoological Park, and will occasionally 
stalk solemnly into my office and, coming close to my 
desk, watch me closely. It has most beautiful gray- 
blue eyes, with long eyelashes (Fig. 199), and if the 
birds of past ages were as comely and as lovable as this 
interesting species, I regret that only their fossil bones 
are left to us. As the Seriema runs down and kills a 
mouse, so the giant Phororhacos, doubtless, overtook 
and slew creatures as large as a deer. Its skull (lig. 7) 
is drawn to the same scale as that of the hving Seriema 
(Figs 8). 
The evolution which has gone on since these epochs 
of old, bringing into being the wonderfully varied forms 
of penguin, ostrich, albatross, peacock, and humming- 
bird, may be summed up in two words which it is well 
to know and remember,—Adaptive Radiation. This is 
the spreading out or radiating of bird-forms descended 
from the ancient stem, into all parts of the earth, each 
coming into contact with a particular environment, to 
adjust itself to which, its various organs and parts exer- 
cise different functions, until the friction of the “struggle 
for existence” has moulded each to its particular niche. 
