AiiT„i9 CONCERNING BIRDS ' TONGUES GARDNER 3 



CARPODACUS MEXICANUS FRONTALIS 



The section is cordiform in shape. The ventral and lateral sur- 

 faces are covered with thin cornified epithelium. The dorsal sur- 

 face is composed of a thick knoblike mass of stratified squamous 

 epithelium through which no glandular ducts were seen to pass. 

 Several large nerve trunks pass through the length of the tongue 

 beneath the branches of the ceratohyals. Nerve corpuscles are 

 found in the posterior end of the tongue. 



It is apparent even from such a brief survey that the tongue must 

 serve, in part in some species at least, as an accessory salivary gland. 

 In addition tactile sense must be ascribed to it, if not even that of 

 taste, as Botezat ^ suggests. 



The variations found in bird tongues are very extensive and often 

 complex, 



Embryological study shows that this organ in birds is primitively 

 a paired structure arising from the second and third visceral arches. 

 This paired condition reflects itself in the hyoid bones, the two fore- 

 most of which, the ceratohyals, being typically unfused and em- 

 bedded in the flesh of the tongue itself. Posterior to this paired 

 position is a median unpaired tract, the basihyal. Upon this 

 foundation are constructed all the elaborate variations to be found 

 among the tongues of birds. Thus the tongues of woodpeckers, 

 which at first sight seem to be constructed on a wholly different pat- 

 tern than that of a robin, are, on last analysis, seen to be but an 

 extensive modification of this rather primitive type, the ceratohyals 

 being fused to a small spearlike tip and the basihyal greatly elon- 

 gated. This is represented superficially by the small barbed sharp 

 tip, the true tongue, while behind this is the fleshy cylindrical 

 extensive basihyal portion often spoken of as the tongue. 



As Lucas ^ pointed out in his work, the tongue of a robin (fig. 1) 

 serves as a ground pattern for many modifications. In this bird it 

 is a slender, horny, lanceolate organ, wider and fleshier at the base 

 than the tip and narrowing to the tip, which is translucent, corni- 

 fied, somewhat split and frayed, with a tendency to curl. 



Posteriorly the tongue ends in a free edge which is deeply con- 

 cave, with the concavity looking caudad and armed with many sharp 

 conical spines which are firm in texture but bend readily. Laterally, 



2 Botezat, E. Die sensiblen Nervenendapparate in den Hornpapillen der Vogel in 

 Zusammenhang mit Studien zur vergleichenden Morphologie und Physiologic der Sinnes- 

 organe, Anat. Anz., vol. 34, 1908. 



Botezat, E. Die sensiblen Nervenendapparate und die Geschmacksorgane der Vogel. 

 Vortrag, gehalten auf der 77. Vers, der Naturf. u. Aerzte in Meran 1905. Referat in den 

 Verhandlungen der Gessellschaft. 



Botezat, E. Morphologie, Physiologie und phylogenetische Bedeutung der Geschmacks- 

 organe der Vogel. Anatomischer Anzeiger, vol. 36, 1910, pp. 428-461. 



» Lucas, F. A. The Tongues of Birds. Rep. U. S. Nat. Mus., 1895, pp. 1003-1020. 



