335 



NATURAL HISTORY. 



The tongue, whose length is thus so extraordinarily increased, is drawn back to its original 

 position within the bill by another pair of muscles, one on each side, which are attached to the basi- 

 liyal. These take their origin from the trachea, around which (as shown in Figs. 2 and 4, r.m.), 

 in many species, they are curiously wound in their course. And, since the bones are at the point 

 of their greatest curvature when at rest, it is obvious that this action of withdrawal is materially 

 assisted by the elasticity of the prolongations of the hyoid bones themselves ; for it is a well-known 

 law that Nature never lets power run to waste, but always utilises forces of mere elasticity or rigidity 

 when by their means the expenditure of nervous energy and muscular contractility can be saved. 



It may be observed that this curious development of the bones of the tongue is not confined 

 to the Woodpeckers ; in the Sun Birds (Nectar iniidce) of the Old World, and the Humrning-Birds 



(Trochilidce) of the New, this same adaptation of means to ends obtains. Even in the Picidse them- 

 selves many variations have been noticed, in addition to those above alluded to; for instance, in 

 the Yellow-billed Woodpecker (Sjihyrapicus* varius) of North America the horns of the hyoid do 

 not reach so far as the eye, so that the tongue, with its bushy tip in this case, is only extensible in 

 a very slight degree; while in the Hairy Woodpecker (Picm villosus) the thyro-hyals curve 

 spirally over the right orbit so as to reach entirely around the eye, to be inserted at its lower 

 posterior margin. 



Considerable difference of opinion exists as to the damage done by Woodpeckers in tapping 

 sound trees, and many a poor bird pays the penalty of his life for his supposed destructive pro- 

 pensities. Mr. Waterton argues strongly on the side of the bird, and alleges that only rotten and 

 unsound trees are attacked for the sake of a nesting habitation, or for the purpose of getting insects ; 

 but that this is not always the case was proved by the writer himself in the spring of 1878, when 

 a boy was sent up to a hole in a beech-tree in Avington Park, in Hampshire. The tree was still 



* vifrvpa, a hammer ; picus, a woodpecker. 



