COMMON CROSSBILL. 21 



them, not in the usual manner, but by drawing the in- 

 ferior maxilla sideways, force open the scales." 



At this stage of the proceeding the aid of the tongue 

 becomes necessary ; and this organ is no less admirably 

 adapted for the service required. The os hyoides, or bone 

 of the tongue, has articulated to its anterior extremity an 

 additional portion formed partly of bone with a horny 

 covering, figures 6 and 7, letter a. In shape it is narrow, 

 about three-eighths of an inch in length, and extends for- 

 wards and downwards, the sides curved upwards, the 

 distal extremity shaped like a scoop, somewhat pointed, 

 and thin on both edges, the proximal extremity ending 

 in two small processes elongated upwards and backwards 

 above the articulation of the bone of the tongue, each 

 process having inserted upon it a slender muscle, 5, figures 

 6 and 7, extending backwards to the glottis, and attached 

 to the os hyoides, which muscles, by their contraction, 

 extend and raise the scoop-like point. Underneath the 

 articulation of this horny and grooved appendage is 

 another small muscle, e, figure 7, which is attached at 

 one extremity to the os hyoides, at the other to the 

 moveable piece, and by its action as an antagonist to the 

 upper muscles, bends the cutting point downwards and 

 backwards ; while, therefore, the points of the beak press 

 the scale from the body of the cone, the tongue, brought 

 forward by its own muscle (genio hyoideus), is enabled, by 

 the additional muscles described, to direct and insert 

 its cutting scoop underneath the seed, and the food thus 

 dislodged is transferred to the mouth ; and it will be seen 

 by a reference to the first figure, that when the mandibles 

 are separated laterally in this operation, the bird has an 

 uninterrupted view of the seed in the cavity with the eye 

 on that side to which the under mandible is curved. 



