336 



SAUKOPSIDA (BIKDS). 



feathers are in the wing attached to the bones of the hand : 

 these are known as " piimary feathers" (iig. 174, A 1-10). 

 Another series arise from the ulna, the secondary feathers (B). 



Fig. 173. — Feather of Bird. 

 C, calamus ; R, rachiu ; K, vexillum ; B, barbs. 



There is a small thumb in the bones of the wing ; this is 

 also provided with feathers, and is called the " bastard wing " 

 (BW). The bases of these large wing-feathers are covered by 

 smaller feathers, the " wing-coverts." The tail-feathers vary in 



