THE HUMMING BIRDS. 



297 



ordinary length of time, and then, by performing these movements in the reverse or- 

 der and direction, it freed itself from the flower, and afterwards proceeded to the ad- 

 joining one, when the same operation was repeated as already described. 



Fig. 7— Bill of Eutoxeres aquila. 



Fig. 8— Bill of Heliotrypha 

 exortis. 



Fig. 9— Bill of Avocettula recurvi- 

 rostris. 



The flower resembles somewhat in form the Roman helmet inverted, and is attached, 

 as it were, by the point of the crest to the stalk. 



Kegarding the recurved bill of Avocettula, the use for which it is 

 adapted is thus coujectured by Mr. Swain son : 



The extraordinary formation in the bill of this beautiful little creature, is without 

 parallel in any laud bird yet described, and presents in miniature a striking resem- 

 blance to that of the avoset. It is almost impossible to conjecture rightly the use of 

 this singular formation ; but it appears to me not improbable, that the principal sus- 

 tenance of the bird may be drawn from the pendent bignonace;e, and other similar 

 plants, so common in South America, whose corolhe are long, and generally bent in 

 their tube ; the nectar being at the bottom, could not be reached either by a straight 

 or a curved bill, though very easily by one corresponding to the shape of the flower. 



Another distinct type of bill is the wedge-shaped, seen in the genera 

 Heliothrix and Schistes, in which the terminal portion (almost the termi- 

 nal half in Heliothrix) is very much compressed, the tip, when viewed 

 from above, forming the finest possible point, as shown below : 



Fig. 10— Bi\lo£ Heliothrix auritus, showing the ex- 

 tremely compressed tip, a being a vertical view. 



Fig. 11— Bill of Schisteg pergonatus. 



Some genera which, instead of extracting their food from flowers, feed 

 upon spiders and other insects, while hovering in the usual manner, 

 which they snatch from the under surface of leaves or from the branches 

 of trees, have the tip of the bill hooked, and the edge of the mandible 

 finely toothed or fringed near the tip, the better to secure their prey. 



Fig. 12 — Bill of \ndrodon cequatorialis. 



The nostrils are situated at the base of the upper mandible, on each 

 side, and are overhung by a distinct scale or operculum. Sometimes 

 this latter is wholly uncovered, and is then very conspicuous ; but 

 oftener it is entirely hidden by short imbricated feathers, entirely con- 



