io6 The Bird 



few thousand years during which man has reigned seems 

 but a day. 



When we study the early structure of some creature, 

 say a bird, we find that before it emerges from the egg 

 the skull is soft and cartilaginous, open and quite differ- 

 ent in shape from what it will be eventually, and it is 

 most startling to find a living creature— a shark— with 



Fig. 82. — Skull of Bald Eagle. Bones light and spongy, fitting for a very active 

 aerial life; orbit very large and brain-case capacious, showing great advance 

 beyond reptilian condition. 



a skull which never gets beyond this condition. It is 

 as if the curtain of eternity had been, for a moment, drawn 

 aside for us, and a glimpse given into the past — a past 

 so remote and clouded that our keenest searches seem 

 to reveal but dim, skeletal forms of weird shapes, which 

 yet we know must have blended and imperceptibly 

 merged, through millions of years, into the present life 

 of the earth. 



Looking at the chicken's skull as a whole, we notice 

 a number of uses which the various parts serve. The 



