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THE POPULAR SCIENCE MONTHLY. 



not resemble that of any of our native birds, being maintained by rapid 

 vibrations of the wings, which enable them to remain apparently mo- 

 tionless in one spot for a considerable time. Their passage from place 

 to j)lace is effected by a series of rapid darts, almost too swift for the 

 eye to follow. Their flight might perhaps be best compared to that 

 of a moth. Like these insects, the humming-birds hover for long over 

 a flower, sipping the honey with their long, thin bill, and in other par- 

 ticulars also in color and form, for example humming-birds and 

 moths offer some remarkable parallels. Representatives of each may 

 be found, to distinguish between which needs a close scrutiny, and 

 which, when on the wing, might perplex the best observer. To all 

 outward appearance the humming-birds are birds when at rest, insects 

 when in motion. 



The tongue of the humming-bird is admirably adapted for extract- 

 ing the honey from flowers, being really a suctorial tongue in the truest 

 sense of the expression. Long and tubular, often bifid and hairy at the 

 tip, this organ serves to catch the insects that may be concealed in the 

 flower (Fig. 22, I). The beak is long, thin, and pointed ; the upper 



Fig. 20. Fig. 21. 



Fig. 22. 

 Humming-birds. Fig. W.Hdiothrix aurita, three fourths natural size. Fig. 31. Hettactinw cor- 

 nutus, three fourths natural size. Fig. 22. I, Sword-beak (Bocimmtes ensifer). II, A flower 

 visited by it for its honey (Datura) ; three fourths natural size. (After Brehm.) 



jaw closes over the edges of the lower jaw, thus forming a kind of tube 

 incasing the tongue. In almost all species the beak is straight or very 

 slightly curved (Figs. 20-22) ; in the sickle-beak alone (the Eutoxeres 

 aquila of the equator, for example) it is sickle-shaped. The length 

 of the beak varies in accordance with the length of the corolla-tube of 

 the flowers habitually visited by the different species. In the Heliac- 

 tinus cornutus of Brazil (Fig. 21) it is 1*5 centimetre long, in the 

 Heliothrix aurita of Minas-Geraes in Brazil (Fig. 20) about two centi- 

 metres. The longest beak among the humming-birds is that of the 



