mTRODUCTION. 



it extends beyond the middle of tlie tail ; moderate, 

 when it reaches nearly or quite to that member; 

 and s//or^ when it does not extend to the base of 

 the tail. 



As relates to their shape — 



Acuminated wings are those adapted for the most 

 rapid and long-continued flight. In wings of this 

 description the first quill is generally the longest, 

 although it sometimes happens that there is scarcely 

 any perceptible difference between that and the 



Fig. 3.— acuminated wing.— swallow. 



second ; the rest, however, rapidly diminish at 

 almost equal intervals, until they reach the lesser 

 quills, which are little more than one-third the 

 length of the exterior primaries. 



It is obvious that in wings of this description 

 nearly the whole power of the stroke is thrown intc^ 

 the primary quills, which are those principally em- 

 ployed in flight. 



Falcated or Sword-shaped wings are only pos- 

 sessed by the Humming-birds. In these, the two 



Fig, i. — FALCATED WING OF HUilMING-BIKD. 



or three primaries are curved towards the ends, 

 which are rather suddenly rounded off", while all the 

 succeeding ones are straight. 



Pointed wings come nearest to those termed acn- 

 mincdecl, and the passage from one of these forms 

 to the other is susceptible of numerous gradations, 

 almost too refined for popular explanation. 



