8 A HISTORY OF BIRDS 



of the opposite side of the barb take the shape of long scrolls, 

 whereof the upper edge is the more deeply curled. When in 

 sifu the two series are so arranged that the booklets are thrust 

 down between the scrolls so that their curled edges are caught 

 thereby. A reference to the accompanying diagrams will 

 make these points clear. The number of these rami or barbs 



I II 



A 



?BUS- 



ILL. 2.-C0NTOUR Feathers showing the Hyporhachis or After-shaft (A) 



I. Of a Pheasant. 



II. Of an Emu. 



depends mainly on the length of the feather. Along the inner 

 web of a Crane's quill feather 38 cm. long, Dr. Hans Gadow 

 counted about 650 rami : he further estimated that every ramus 

 of this feather bore about 600 pairs of radii (barbules) mak 

 ing nearly 800 000 radii for the inner web alone, and more 

 than a million for the whole feather. 



The contour feathers of most birds bear what is known 



