742 



PHYLUM CHORDATA : CLASS AVES — BIRDS 



The skeleton of the wing includes the stout humerus, 

 the separate radius and ulna (the latter the larger), two 

 free carpals, a carpo-metacarpus of three metacarpals fused 



Fig. 442. — Pectoral girdle and breastbone of an eagle. — 



From a Specimen. 



SC, Scapula ; F., foramen triosseum enclosed by scapula, coracoid, and clavicle ; 

 G.C., glenoid cavity, formed by scapula and coracoid ; CO., coracoid, articulating 

 with the sternum ; CL., one of the clavicles ; ICL., interclavicle, connected by 

 ligament with the manubrium of the sternum ; K., keel or carina of the sternum ; 

 ST., body of the sternum ; R., notches for the insertion of ribs. 



to one another and to some carpal elements, and three 

 digits — the thumb with one joint, the first finger with two 

 joints, the second with one. In adaptation to flight, the 



