132 SOME HYOID EINTb. 



gested to him that the hyoid cornua might 

 aid Picus in hearing. We discussed the mat- 

 ter for a moment, and the subject passed, but 

 it came again and again to my mind, till at 

 length I set about making a systematic study 

 of it. 



In the case of the hairy woodpecker the 

 tongue muscles are so arranged that by a very 

 simple action the tongue may be drawn far 

 back into the mouth-cavity, near the throat. 

 This is true in a greater or less degree of all 

 the woodpeckers having the specialized hyoid- 

 ean process, but in the hairy species it is ex- 

 tremely marked. 



The true woodpeckers, from the great ivory- 

 bill down to the little downy species (Pubes- 

 cens), have poor ears, and are forced to de- 

 pend upon their excellent eyes for detecting 

 the approach of an enemy, hence the contin- 

 ual motion of the head, which has given color 

 to the statements of Buffon. The log-cock, 

 which a few years ago was one of the com- 

 monest birds of the Western "deadenings," 

 makes its great scarlet head-tuft fantastically 

 conspicuous by tossing it this way and that 

 in its vigilant watchfulness. 



Nearly all the species have the habit of 

 making a vibrating noise by striking an elas- 

 tic piece of wood with the bill. This singular 

 call serves the woodpecker in the place of a 

 song. To his heavy, dull ears the sound 

 doubtless is very pleasing. To understand 

 this, take a string of the size of a guitar 

 string, and a foot long, place one end between 

 your teeth and the other between the thumb 

 and index finger of the left hand, draw it taut, 

 and strike it lightly with the right thumb. 

 You will hear a sound quite inaudible to an- 

 other person, though close to you. This aud- 

 itory phenomenon is caused by the vibrations 

 of the string being imparted to the lower jaw- 



