INTRODUCTION 



XXV 



'pItl.M' 



mapped out into certain areas such as are indicated 

 in Fig. 4. 



So far we have spoken only of the feathers which 

 form the outer surface-covering of the bird, the "con- 

 tour" feathers, as they 

 are called because they 

 form the contour or out- 

 line of the body. But 

 besides these there are no 

 less than three other dis- 

 tinct kinds of feathers 

 — d own feathers, filo- 

 pliunes, and powder- 

 down. 



Down feathers in, 

 many birds are conspicu- 

 ous by their absence, 

 and are developed most 

 abundantly in water- 

 birds, such as Ducks, for 

 example, growing not 

 only between the feathers, but over the otherwise bare 

 spaces as well, so as to form a thick undergrowth, 

 answering to the under-fur of seals, for instance. 



Filo-plimies appear to be present in all birds. They 

 are the long, hair-like growths so conspicuous in the 

 common Fowl when plucked. In some birds they at- 

 tain such a length as to extend beyond the contour 

 feathers, forming, as in some Cormorants, long, white, 

 delipate plumes. 



The powder-down feathers are foiind only in a few 

 groups, such as the Herons and Bitterns, and some 



Fig. 4. — Diagram of a bird, 

 showing the different 

 areas of the body. 



