36 THE TONGUES OF WOODPECKERS. 



particular kind of food which could be best obtained by some special 

 adaptive feature would naturally have more influence as a modifying 

 agent, even if indulged in for only a short time, than a general diet 

 for a long period, since the one would be positive in its efiects, the 

 other negative. 



As the hyoid bone is the framework on which the tongue is built, it 

 will be well to note some of its characteristic features in the wood- 

 peckers before proceeding to the modifications of the tongue itself. 

 The hyoid is so constructed as to combine the two characters of length 

 and strength that are needed for extensile purposes. The front of the 

 hyoid is formed by the short, fused cerato-hyals, although a groove, or 

 in some cases a perforation, indicates the double origin of this bone. 

 The basi-hyal is usually very long and very slender and the cera.to- 

 branchials abut upon its posterior end, the basi-branchial being absent, 

 nor have any indications of this bone been found even in very young 

 specimens. The cerato-branchials and epi-branchials are variable, 

 especially the latter, which, as in the Sapsucker {Sphyrapicus), may be 

 no longer than in many Passeres, or, as in the Flickers (Colaptes), reach 

 the maximum length among birds. The epi-branchials curve up over 

 the back of the skull, meet on its summit, and continue on toward 

 the forehead. In other long-tongued birds, as in the humming bird 

 (TrocMlus), for example, the apposed bones reach to the base of the 

 bill, but in the longest-tongued. woodpeckers they turn to the right, 

 pass through the right narial opening, dipping under the nostril, and 

 thence continue quite to the tip of the bill, so that in these species the 

 extreme possible length of tongue is reached unless some other device 

 is resorted to.' The cerato-branchials lie side by side when the tongue 

 is protruded, and even when it is withdrawn they are posteriorly but 

 little separated. The general character of the hyoid is constant in all 

 species examined, but, as just stated, the proportions of its component 

 parts vary, the extremes being represented by the Sapsucker {Spliyra- 

 picus) and Flicker (Colaptes), both of which are figured (PI. Ill, figs.l, 3). 



Externally the tongue consists at the tip of a horny portion more or 

 less barbed along the edges ; this is followed by a section covered with 

 tough skin bearing on the upper surface a long patch of minute points, 

 wliile the basal portion is clothed with smooth, elastic skin, which is 

 more or less wrinkled tranversely when the tongue is retracted. The 

 skin covering the base of the tongue is reflected, forming a sort of sheath, 

 into which the basal part of the tongue is withdrawn when at rest. 

 The shape of the patch of minute points, as well as the number and 

 character of the points themselves, seems to vary in different species, 



' It would appear that a method is already in use by ■which the length of the tongue 

 can he greatly increased, and this is the curling of the free ends of the epi-branchials 

 into a spiral. Although I have never met with a specimen in which the hyoid was 

 so arranged, both Dr. Bryant and Mr. Wm. Palmer have recorded specimens in which 

 the hyoid encircled the eye. Dr. Bryant's paper, entitled "Eemarks on Spliyrapious 

 varius, Linn./' appeared in Proc. Bost. Soc. Nat. Hist., Vol. X, 1864-'66, pp. 91-93. 



