SKELETON OF BIRD 



741 



p. rnx • 



extensions of the premaxillae and maxillse. The interorbital 

 septum is formed chiefly 

 from the mesethmoid, 

 but also from the pre- 

 sphenoid. From the 

 tympanum to the inner 

 ear extends the rod-Hke 

 columella. The lower 

 jaw originally consists of 

 four membrane bones — 

 dentary, splenial, angu- 

 lar, and surangular ; and 

 one cartilage bone — 

 the articular. The hyoid 

 consists of a flat " body," 

 with anterior and pos- 

 terior " horns," the latter 

 derived from the first 

 branchial arch. 



The pectoral girdle 

 consists of sabre-like 

 scapulae extending dor- 

 sally over the ribs, of 

 stout coracoids sloping 

 ventrally and articulating <^j 

 with the sternum, of the 

 clavicles which are united 

 by the interclavicle to 

 form the merrythought 

 or furcula. The opening 

 left where the upper 

 ends of the clavicles 

 touch the scapula and Fig. 441^.— Under surface of gull's 

 COracoid is called the skull.-From Royal Scottish Museum, 

 f . • Edinburgh. 



foramen triosseum. ^ 



The sternum bears a 

 conspicuous keel, is pro- 

 duced laterally and pos- 

 teriorly into two xiphoid 

 processes, and bears articular surfaces for the coracoids 

 anteriorly, for the sternal ribs laterally. 



C 



Condyle ; b.t., basitemporal ; b.s., basi- 

 sphenoidal rostrum ; pt., pterygoid ; pa., 

 palatine ; v., vomer; p.mx., premaxilla ; mx., 

 maxilla ; j., jugal ; q.j., quadrato-jugal ; q., 

 quadrate. 



