1008 



REPORT OF NATIONAL MUSEUM, 1895. 



the tube is single; in Yestiaria the edges pass by and the tube becomes 

 triple, while by division it may terminate in two or four tubes, as the 

 case may be. 



The real effectiveness of a tubular tongue depends not only on the 

 tongue itself, but on the action of the hyoid and its controlling muscles, 

 just as the usefulness of a pump does not lie in the pipe, but in the 

 valves. The manner in which suction is eftected has been well' 

 described by Doctor Gadow,^ and is, in substance, as follows : By the 

 contraction of the mylo and serpio hyoid muscles which underlie the 

 tongue, that organ, together with the larynx, is pressed up against the 

 roof of the mouth. The tongue is then protruded and the larynx and 

 back part of the tongue depressed, thus creating a vacuum between 

 tongue and palate, and into this vacuum will flow any liquid into which' 

 the tip of the tongue may have been inserted. The fringing of the 

 tip of the tongue, or its conversion into a spiral brush, causes liquid to 



Fig. 4. 



ascend to the tubular portion of the tongue by capillary attraction, and 

 thus overcomes any tendency of air to enter the tongue and prevent 

 suction. 



If we go back to what we may call the primitive pattern of tongue 

 and make the upper surface thick and fleshy instead of thin and horny, 

 we will have such a tongue as characterizes many, if not the majority, 

 of seed-eating birds, while between the two come such tongues as those 

 of the swifts and swallows, owls and goatsuckers. The amount of vari- 

 ation in these last named groups is not great, and there is no wide 

 departure from what may be termed the standard pattern. The tongues 

 of the titmice and nuthatches may either be looked upon as modifica- 

 tions of the sparrow type, or as having a pattern of their own. Those 

 of the titmice (Plate 1, fig. 14) suggest a four-tined pitchfork, and can 

 be better understood from the figure than from any description. Those 



'Proc. Zool. Soc. Lond., 1883, pp. 62-69. 



