8 THE STRUCTURE AND LIFE OF BIRDS CHAP. 
Fic. 2.—Skeleton of Fowl (after Marshall and Hurst). 
A, acetabulum; aT, atlas vertebra; Ax, axis vertebra; cL, clavicle; cm, carpo- 
metacarpus; CO, coracoid; cR, cervical rib; nz, 2, 3, 4, digits; pr, dorsal nb; 
FE, femur; HU, humerus; Hy, hyoid bone that supports the tongue; 11, ilium 3 
Is, ischium ; kK, keel of sternum}; Mc, 1, 2, 3, metacarpals; MT, first metatarsal; 
pb, pubis; py, pygostyle ; Rr, radius; Rc, radial carpal; sc, scapula ; sp, spine; SR, 
sternal piece of rib; TM, tarso-metatarsus; TT, tibio-tarsus; u, ulna; uc, ulnar 
carpal; up, uncinate processes. 
