546 



RUBY-THROATED HUMMING BIRD. 



hyoid bone at the junction of the apo-hyal and cerato-hyal, whence it pro- 

 ceeds all the way to the tip of the latter, the muscle and bone being in- 

 closed in a very delicate sheath, which is attached to the subcutaneous 

 cellular tissue between the nostrils. The tongue, properly so called, 

 moves in a sheath, as in the Woodpeckers ; its length is 10 twelfths. 

 When it is protruded, the part beyond this at the base appears fleshy, 

 being covered with the membrane of the mouth forming the sheath, 

 but the rest of its extent is horny, and presents the appearance of two 

 ylinders united, with a deep groove above and 

 another beneath, for the length of 3 twelfths, be- 

 yond which they become flattened, concave above, 

 thin-edged and lacerated externally, thick- edged 

 internally, and, although lying parallel and in con- 

 tact, capable of being separated. This part, be- 

 ing moistened by the fluid of the slender sa- 

 livary glands, and capable of being alternately ex- 

 serted and retracted, thus forms an instrument for 

 the prehension of small insects, similar in so far to 

 that of the Woodpeckers, although presenting a 

 dififerent modification in its horny extremity, which 

 is more elongated and less rigid. All observers 

 who have written on the tongue of the Humming 

 Birds, have represented it as composed of two cy- 

 lindrical tubes, and the prevalent notion has been that the bird sucks 

 the nectar of flowers by means of these tubes. But both ideas are in- 

 correct. There are, it is true, two cylindrical tubes, but they gradu- 

 ally taper away toward the point, and instead of being pervious form 

 two sheaths for the two terminal parts or shafts of the glosso-hyal por- 

 tion of the tongue, which run nearly to the tip, while there is appended 

 to them externally a very thin-fringed or denticulate plate of horny sub- 

 stance. The bird obviously cannot suck, but it may thrust the tip of 

 the tongue into a fluid, and by drawing it back may thus procure a por- 

 tion. It is, however, more properly an organ for the prehension of small 

 insects, for which it is obviously well adapted, and being exsertile to a 

 great extent enables the bird to reach at minute objects deep in the 

 tubes and nectaries of flowers. That a Humming Bird may for a time 

 subsist on sugar and water, or any other saccharine fluid, is probable 

 enough ; but it is essentially an insect-hunter, and not a honey-sucker. 



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