THE TONGUES OF BIRDS. 



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and renew the horiiy covering of their beaks, is not known to me, but 

 if this is not the case, the growth of the tongue must be comparatively 

 rapid to prevent it from being worn to the quick. 



The tongues of the North American honeycreepers of the genus 

 Certhiola are an elaboration of the warbler type, being finer and more 

 complicated in detail, long and slender, much hollowed out toward the 

 tip, deeply cleft, and decorated with long incurved featherings. An 

 Australian honeysucker, Acanthorhynehus tenuirostris, carries the fining 

 down of parts to an extreme, having a delicacy of structure which 

 can be appreciated only with a glass. The tongue of still another 

 genus of ISTorth American honeycreepers, Cocrcba (fig. 3 c), differs 

 from those just described in the matter of detail by splitting the tongue 



Fig. 3. 



more deeply and increasing the length of the feathering which rolls 

 inward from either edge so that the tongue ends in two spiral brushes 

 of extreme delicacy. The Hawaiian and Australian honeysuckers 

 show a still farther advance on this, for in them each of the main 

 branches of the tongue is cleft in twain, and these may again bifurcate 

 so that the tongue ends in four or eight small spiral brushes. By a 

 very little modification a true suctorial tongue, such as that of the sun- 

 birds, Cinnyris, or of the genus Hemignathus (fig. 3 b), may be derived 

 from that of the "srarbler type. If, instead of splitting and feathering 

 the tip, the edges of the tongue are rolled upward and inward until 

 they meet, a tube will be formed, and this tubular tongue, as well as 

 the others, is subject to various modifications and may become quite 

 complicated. In the sunbirds the edges simply touch each other and 



