of France, Switzerland, and Styria). This in turn is derived from an older, generalized ape form which lived in the older Miocene period, and which maybe regarded as the common ancestor of the Old World apes, both the tailed Cynopitheci and the tailless Anthropomorpha. Among the latter we now recognize the two living species of the gibbon which stand very near to Pliopithecus, as well as fossil anthropoid apes that lead directly to Pithecanthropus. Such an intermediate stem form is Pliopithecus sivalensis, whose skeleton was found in the early Tertiary layers of eastern India in the Pliocene Siwalik strata.
For forming a correct judgment concerning this important Pithecanthropus and its immediate position between the anthropoids and man, two features are especially valuable; first, the close resemblance of the femur to that of man, and second, the relative size of the brain. Among the few anthropoid apes yet living the gibbons appear to be the lowest and oldest, standing nearest the stem-form of all the Anthropomorpha; they are also the most generalized and appear especially adapted to illustrate the "transformation of apes into man." The gibbons more than the other anthropoids have the habit of voluntarily assuming the upright position, whereby they walk upon the entire sole of the foot and use their long arms as balancing poles. The other modern apes (orang, chimpanzee, and gorilla) seek the upright position, and when they use it do not tread upon the entire sole but upon the outer edge of the foot; they also have in other respects more specialized characters, adapted especially to their tree climbing life. It is thus explained why it is that it is exactly the femur, in Hylobates and Pithecanthropus, that is much more human in form than that of the gorilla, the orang, and the chimpanzee.
But also the skull, that "mysterious vessel" of the organ of the soul, approaches nearest the human proportions both in Pithecanthropus and in the gibbon in important particulars—the rough, bony crests which the skulls of the other anthropoids show are wanting. The relative size of the brain (in proportion to that of the entire body) is in the latter only half as great as it is in the gibbon. The capacity of the skull of Pithecanthropus is from 900 to 1,000 c.c., therefore about two-thirds the capacity of an average human skull. On the other hand: the largest living anthropoids show a capacity half as high as this—500 c.c. So the capacity of the skull and consequently the size of the brain is in Pithecanthropus exactly midway between that of the anthropoid apes and the lower races of mankind; and the same is also true for the characteristic profile line of the face. In this respect compare the skulls of the lowest and most pithecoid races of man. Among these the still living pygmies, the little Veddahs of Ceylon and the Akkas of Central Africa, are of great interest. An unprejudiced comparison of all these anatomical facts shows in no ambiguous manner the character of Pithecanthropus as a true intermediate form between anthropoid apes and man; he is the long sought for and much discussed "missing link" in
