"Right pectoral arch of a bird. s, scapula; c, coracoid; gl, glenoid, the cavity for head of humerus; cl, clavicle; hc, hypecleidium. In situ, the right end of the figure should tilt up a little.The pectoral arch is that bony structure by which the wings are borne upon the axial skeleton. It is to the fore limb what the pelvic arch is to the hind limb; but is disconnected from the back-bone and united with the breastbone, whereas the reverse arrangement obtains in the pelvic, which is fused with the sacral region of the spine. Each pectoral arch of birds consists (chiefly) of three bones: the scapula and coracoid, forming the shoulder-girdle proper, or scapular arch; and the accessory clavicles, or right and left half of the clavicular arch." Elliot Coues, 1884

The Right Pectoral Arch of a Bird

"Right pectoral arch of a bird. s, scapula; c, coracoid; gl, glenoid, the cavity for head of humerus;…