20 FRINGILLID^E. 



turn, and passes downward to be inserted upon the pro- 

 jecting 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 down- 

 wards and backwards, is inserted upon the omoideum, 

 both muscles by their contraction pulling the os quadratum 

 forwards, and thus elevating the upper mandible. The 

 depressors of the lower jaw, and the elevators of the upper 

 jaw, therefore, act together to separate the mandibles. 



To close the mandibles, the temporal and pterygoid 

 muscles elevate the lower jaw, assisted by two slender slips, 

 marked d, d, figure 2, which, extending forwards to the 

 superior maxillary bones, act in concert by bringing them 

 down. 



When the lateral motion is required, the great pyra- 

 midal muscle on the right side pulls the extremity of the 

 lower jaw, to which it is attached backwards ; the ptery- 

 goid muscle of the left side at the same time powerfully 

 assisting by carrying that side of the lower jaw inwards. 



Having thus described the muscles of the mandibles in 

 birds generally, and their peculiar mode of action in the 

 Crossbill, I shall quote Mr. Townson's description of the 

 manner in which they are made subservient to the use of 

 the bird in feeding. " The great pine forests, such as the 

 Hartz in Germany, are the natural places of residence of 

 the Crossbeaks, and the seed of the cones of these trees 

 their food, and it is to pull out the seeds from between the 

 squamse, or scales of the cones, that this structure is given 

 them. Their mode of operation is thus : They first fix 

 themselves across the cone, then bring the points of the 

 maxillae from their crossed or lateral position, to be im- 

 mediately over each other. In this reduced compass they 

 insinuate their beaks between the scales, and then opening 



