INTRODUCTION. 



XI 



exceed the tail in length, unless, as in some cases, that member 

 has an extraordinary development. "When the wing is spread it 

 may be noticed that the outline is very much curved; the feathers 

 are closely set; the shafts or quills being very strong and elastic, 

 and the webs firm and full; the air from above passes easily through 

 them, but pressure from beneath renders them close and compact 

 as a piece of whalebone. We give below a cut of two of these 

 feathers, in order to shew their form and structure. 



Nearly all the muscular power of this creature's small anatomy 

 is concentrated in the organs of flight, and a wonderful facility 

 of performing its evolutions in the air is the result; it darts hither 

 and thither with the swiftness of light, and when suspended over 

 a flower, so rapidly do the wings move, that one might believe them 

 to be quite motionless, were it not for the changeful lustre that 

 plays about them, as the rays of the sun strike them at different 



angles, and for the low drowsy kind of sound, similar to the hum 

 of bees, which they emit, and from which they derive their coTn- 

 mon name. The length of time, too, during which they remain 

 on the wing is truly astonishing; indeed, they seldom appear to 



