136 SOME HYOID HINTS. 



cornua are elongated very little, if any, be- 

 yond the base of the skull. His food is 

 selected by sight, and he has no need for a 

 specialized hyoidean apparatus. Indeed all 

 of the species of woodpeckers that are not de- 

 pendent upon boring into wood or into the 

 ground, and that therefore do not have to 

 locate their food or test its quality without 

 seeing it, have the hyoid bones less developed 

 than in Picus. 



The protrusion of the tongue is the more 

 obvious function of this hyoidean peculiarity, 

 but the more obscure function of aid to the 

 dull senses of taste and hearing is not there- 

 fore less important. 



It would not be of particular interest in this 

 connection to go into the minutiae of the many 

 slight variations of the tongue-peculiarity ob- 

 servable in different species. I have given 

 the extremes, the mean and, in the instance 

 of Colaptes, a case of curious intermedin 1/3 

 specialization (where an extreme might have 

 been expected like that of Spheropicus) for 

 meeting the exigency of a singular habit. 



It is impossible, in a paper addi-essed to the 

 popular understanding, to make minute com- 

 parisons in anatomy, but the facts upon which 

 I insist may be formulated as follows : 



1st. The picidsean development of the hyoid 

 cornua in the genus Picus has for its second- 

 ary function a mechanical and perhaps sen- 

 sory aid to hearing. 



2d. Such development in the genus Colaptes 

 is in aid of the sense of taste. 



So minute and obscure are the nerve lines 

 of the hyoid sheath, and so complicated are 

 the wisps of motor nerves controlling the 

 tongue of the woodpecker, that one may not 

 speak with perfect knowledge as to where mere 

 motor action leaves off, and the telegraphy 

 of sense begins, but it appears to me that to 



