To come to the limbs, we find the _shoulder-blade_ presenting three _epiphyses_, one for the _coracoid_ process, one for the _acromion_, and one for the lower angle of the bone, the ossification of which begins soon after puberty, their union with the body of the bone taking place between the ages of twenty-two and twenty-five years. The _clavicle_ has an _epiphysis_ at its sternal end, which begins to form between the eighteenth and twentieth years, and is united to the rest of the bone a few years later. The consolidation of the shoulder-bone (_humerus_) is completed rather earlier; the large piece at the upper end, which is formed by the coalescence of the ossific centres of the head and two tuberosities, unites with the shaft at about the twentieth year; whilst its lower extremity is completed by the junction of the external condyle, and of the two parts of the articulating surface (previously united with each other), at about the seventeenth year, and by that of the internal condyle in the year following. The superior _epiphyses_ of the arm-bones (_radius_ and _ulna_) unite with their respective shafts at about the age of puberty; the inferior, which are of larger size, at about the twentieth year. The _epiphyses_ of the _metacarpal_ and _phalangeal bones_ (those of the hand and fingers) are united to their principals at about the twentieth year. In the _Lower Extremities_, the process of ossification is completed at nearly the same periods as that of the corresponding parts of the Upper. The consolidation of the hipbones (_ilium_, _ischium_, and _pubis_) to form the _os innominatum_, by the ossification of the triradiate cartilage that intervenes between them in the socket of the thigh (_acetabulum_), does not take place until after the period of puberty; and at this time additional _epiphyses_ begin to make their appearance on the crest of the _ilium_, on its anterior inferior spine, on the tuberosity of the _ischium_, and on the inner margin of the _pubes_, which are not finally joined to the bone until about the twenty-fifth year.[88] The concurrence of these conditions in the skeleton, the nearly balanced ratio of the bloods, the perfected dentition, the beard, the deepened voice, the prominent larynx, and the stature, combine to point out, with infallible precision, the age of this Man, as between twenty-five and thirty years. So far, then, we can with certainty trace back the history of this being, as an independent organism; but did his history then commence? O no; we can carry him much farther back than this. What means this curious depression in the centre of the abdomen, and the corrugated knob which occupies the cavity?[89]