I INTRODUCTORY 3 



The bodies and brains of birds arc suited to their 

 full and varied life. Their circulation is rapid, their 

 temperature higher than that of mammals, their lungs, 

 though small, are probably the most efficient in the 

 animal kingdom, their bones and their muscles have 

 been adapted for purposes of flight, running, or swim- 

 ming, they have brains that are, comparatively 

 speaking, highly developed. 



And yet the bird is a near relation of the lizard. 

 He is descended, unless nearly all our great authori- 

 ties are at fault, though not from any existing reptile, 

 yet from ancestors that were definitely reptilian. 

 And yet how enormous is the difference between 

 these descendants from the same stock ! For the two 

 lines must meet if we trace them upward far enough. 



A lizard is limited to earth, and even there his gait 

 is an undignified shuffle. True, he slips with un- 

 surpassed nimbleness into his hiding-place on a hot 

 day when the sun has warmed his sluggish blood. 

 But though he be the fastest of lizards, many a bird of 

 no great size is a better runner, and could, without 

 having recourse to the magic of wings, easily distance 

 him in a race of more than a few yards. His forehead 

 is low, hardly rising above his nose, showing, if 

 other evidence were wanting, that his intellect is feeble. 

 Indeed, in this respect, he is hardly above the boa- 

 constrictor who mistakes his blanket for a rabbit 

 and swallows it. His blood is cold, and when the 

 thermometer sinks a little below the freezing-point 

 he torpifies. In the winter he merely exists, while the 

 bird lives. He eats but little and digests slowly — 

 a sign of the sluggishness of his whole life. Both 



B 2 



