SKELETON. 
663 
_ The sternum bears a .conspicuous keel, is produced 
laterally and posteriorly into two xiphoid processes, and 
Fic. 366.—Side view of pelvis of cassowary, 
Z2., ium ; /sch., ischium ; Pé., pubis; Ac., acetabulum. 
bears articular surfaces for the cora- 
coids anteriorly, for the sternal ribs 
laterally. 
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 
a i o one another 
, oc cvensents, and three 
digits—the thumb with one joint, the 
first finger with two joints, the second 
with one. In adaptation to flight, the 
wing of a bird has much less flexibility 
of parts than the arm of a Mammal. 
The radius and ulna do not move upon 
each other. 
The pelvic girdle consists of dorsal 
ilia fused to the complex sacral region, 
of ischia sloping backwards, and of 
pubes running parallel to the ischia. 
The incomplete ossification of the 
acetabulum and the absence of ventral 
symphyses are noteworthy. 
The hind-limb consists of a short 
stout femur, a tibia to which the 
proximal tarsals (astragalus and os 
calcis) are fused (forming a tibio-tar- 
sus), an incomplete fibula joined to 
Fic. 367.—Bones of 
hind-limb of eagle. 
J, Femur ; ¢.2.,tibio-tarsus ; 
Jo., fibula; a@., ankle- 
joint; 7.¢., tarso-meta- 
tarsus ; 77.2’., first meta- 
tarsal (free). 
