14 Forest Birds. 
running along the concavity of the bone, and as 
this muscle contracts, it straightens the sheath and 

Pre. 1. 
Head of Green Woodpecker, showing sheath passing round 
head, and joined to skull in nostril. 
From nature. One-half natural size. 
so forces out the tongue to a considerable distance 
beyond the point of the bill (Fig. 2). Thus when 
the bird sees an insect in a hole or under the bark, it 

Fie. 2. 
Head of Woodpecker, showing tongue extended and (@) gland. 
From nature. One-half natural size. 
shoots out its wormlike tongue and transfixes the 
insect, the barbs preventing its prey from slipping 
