XITT 



PHYLUM CHORDATA 



383 



contact (A, B). In this way the parts of the feather are so bound 

 together that the entire structure offers great resistance to the air. 

 Among the contour feathers which form the main covering of the 

 Bird and have the structure just described, are found filoplumes 

 (Fig. 1023, B), delicate, hair-like feathers having a long axis and a 



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few barbs, devoid of locking apparatus, at the distal end. Nestling 

 Pigeons are covered with a temporary investment of down-feathers 

 (C), in which also there is no interlocking of the barbs : when these 

 first appear each is covered by a horny sheath like a glove-finger. 



Feathers, like scales, arise in the embryo from papillae of the 

 skin (Fig. 1025, A, Pap.\ formed of derm with an epidermal covering. 



