CROSS-BEAKS. 155 



chough builds, I know, all along the chalky cliffs 

 of the Sussex shore. 



so called from their particular shape. These three muscles, 

 all of which have their origin in the occipital portion of 

 the cranium, are inserted by strong tendons on the 

 under and back part of each extremity of the lower 

 jaw, behind the centre of motion, and consequently, by 

 their simultaneous contraction, raise the point to which 

 they are attached, and depress the anterior part of the 

 mandible. The lower portions of the ossa quadrata are 

 pushed somewhat forwards by this compression, assisted 

 by two small muscles ; one of these, a small flat muscle, 

 arises from the septum of the orbits, behind the small 

 aperture observed in the septum, and passes downwards to 

 be inserted upon the projecting styloid process of the os 

 quadratum. The second is a small pyramidal-shaped 

 muscle, arising also from the septum, anterior to the other 

 muscle, and, passing downwards and backwards, is inserted 

 upon the omoideum, both by their contraction pulling 

 the os quadratum forwards, and thus elevating the other 

 mandible. The depressors of the lower jaw, and the 

 elevators of the upper, therefore, act together to separate 

 the mandibles. To close the mandibles, the temporal and 

 pterygoid muscles elevate the lower jaw, assisted by 

 slender slips, which, extending forwards to the superior 

 maxillary bones, act in concert, by bringing them down. 

 When the lateral motion is required, the great pyramidal 

 muscle on the right side pulls the extremity of the low r er jaw 

 to which it is attached backwards, the pterygoid muscles on 

 the left side at the same time powerfully assisting, by carry- 

 ing that side of the lower jaw inwards." 



Mr. Yarrel next goes on to explain the uses of the 

 tongue. Their food is the seeds of the different fir cones ; 

 and their mode of operation, when proceeding to extract 

 them, is this: They first fix themselves across the cone; 

 then, bringing the points of the maxilla from their crossed 

 or lateral position to lie immediately over each other in 

 this reduced compass, they insinuate their beaks between 

 the scales, and then opening them, not in the usual manner, 

 but by drawing the inferior maxilla sideways, force open 

 the scales. Mr. Yarrel then proceeds: " 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 arti- 



