xvi. 3 



FEATHERS 



433 



Fig. 249. Various types of feather. 



A, filoplumes; B, nestling down-feather; C, primary wing feather of pigeon; D, permanent 



down feather; E, feather with free barbs; F, emu's feather with long aftershaft; G, contour 



feather of pheasant with aftershaft. (Partly after Thompson, The Biology of Birds, 



Sidgwick & Jackson, Ltd.) 



may be of various types, prefiloplumes, preplumules, and prepennae; 

 finally, the adult feathers (teleoptiles). 



Each feather, of whatever type, is formed from a dermal papilla or 

 follicle, over whose surface keratin is produced. In down-feathers the 



