10 PROCEEDINGS OF THE NATIONAL MUSEUM vou 67 



7. Flower frequenters (fig. 19) have most complex tongues. 

 Among these we find the fringed split and tubular tongues of the 

 Drepanididae, the Nectariniidae, Dicaeidae, some of the Icteridae, 

 the Zosteropidae, and the Meliphagidae. In this group also falls 

 the Trochilidae. Finally a most remarkable adaptation is found in 

 the flower frequenting parrots of the family Triehoglossidae (fig. 

 70), where the tongue is curled at the tip and supplied with a stiff 

 brush of vibrissae. 



The correlation of such tongues with a nectar, pollen, insect, diet 

 is easy to see. Of further interest is the fact that members of most 

 of these families possess the ability to very greatly extend the 

 tongue. The hyoid bones are prolonged over the occiput in the same 

 manner as that adopted by the woodpeckers, and like the latter may 

 even extend well down to the base of the bill. 



8. Rudimentary. Finally a natural group is formed of tongues 

 that have lost the greater part or all of their function, a condition 

 found among many families. Thus birds that bolt their food whole 

 have this organ often merely a little fleshy cylinder a few milli- 

 meters long and no wider. This structure prevails in many of the 

 fish eaters, as the booby, pelican, stork, gannet, darter (fig. 20), 

 man-of-war bird, cormorant, and the like. Again in the huge-billed 

 hornbills we find only a small and unimportant tongue; neither is 

 this organ very large or of much apparent use in their allies, the 

 kingfishers, or again in many of the Caprimulgidae, in which family 

 it is often to be found small and rather simple in structure. 



It is apparent in such a review that in a large number of forms 

 tongue structures can be correlated with some special diet and the 

 method of its procurement as might well be expected of an organ 

 so intimately concerned with the function of obtaining food. The 

 exceptions, however, are numerous and present most interesting prob- 

 lems. For example, no special adaptation is to be noted in the 

 tongues of gulls, rails, sandpipers, and the like unless, as it seems 

 not at all improbable, special tactile or even taste sense is located in 

 them. Added to these are certain odd and rather complex tongues 

 the unusual shapes of which are difficult to explain. An instance is 

 this organ in the fruit-eating trogons (fig. 21). It is triangular, 

 thick, heavy, horny tipped, with a central groove bordered by dis- 

 tinct ridges and heavily armed posteriorly with spines. The mot- 

 mots have a long slender structure, thin and horny and much frayed 

 laterally, somewhat resembling that found in toucans (fig. 87), in 

 which birds, again, a most curious featherlike organ is found with the 

 frayed lateral margins directed anteriorly, the significance of which 

 can not be evaluated at present. 



