398 



THE PIGEON. PHYLUM CHORDATA 



^^Ci- 313. — Photographs of a tame pigeon in slow flight, xsinety-one pictures 

 per second. — From Brown, Journ. Exp. Biol. 25 (1948) 322. 



1. Early part of downbeat. Alula opened. Forward force on primaries i and 2. 



2. Wing horizontal 



3. Beginning of forward swing. 



4. End of downward movement, forward movement continuing. 



5. Beginning of upstroke. 



6. Upstroke. Primaries uncurved — no external work being done. 



