BILL OF THE CROSSBILL. 191 



Before stating how this bill is used, we must advert 

 to the tongue, which is an important part of the 

 whole organ. Fig. 2, on the cut is an outline of the 

 upper side. A portion of the tip from a to b is in the 

 form of a scoop, raised at the sides, and thin and 

 rounded at the extremity. This scoop is composed 

 of horn, supported by a particular bone, which is 

 articulated to the os hyoides or common bone of the 

 tongue c c, at the point b; and one set of muscles bind 

 the joint at b, and thereby depress the point of the 

 scoop, and draw it backwards; while another extends 

 the joint, and projects and elevates the scoop. The 

 tongue has thus what may be called a sort of elbow 

 joint, and the scoop performs the office of a sort of 

 hand in picking up those substances to which access 

 is procured by the oblique motion of the mandibles. 

 The bill thus performs the functions of two bills ; 

 and one of them could not be performed by a bill of 

 any other construction. 



The way in which the points of the mandibles 

 move, draws them into any substance of which they 

 can take hold. If that substance is of a texture not 

 to be cut by the points, they split it open by their 

 wedge-like action ; and if it is a softer substance, they 

 at the same time cut it in the cross direction. What- 

 ever may be the depth of the opening, the eye also 

 sees to the bottom of it, and the scoop of the tongue 

 can reach it. The upper mandible is the part of the 

 bill at rest, and therefore to whichever side it bends, 

 the head is bent to the other, and the eye on it com- 

 mands all the space, which the point of the under 

 mandible pushes open, from the contact to the greatest 

 extent in crossing. 



Crossbills are found chiefly in the extensive pine 

 forests of the northern latitudes, where they live upon 



