e monkeys, whose most important characters
have been handed on to the present day New World monkeys. How the
different genera are to be arranged within the general scheme
indicated depends in the main on the classificatory value attributed
to individual characters. This is particularly true in regard to
_Pithecanthropus_, which I consider as the root of a branch which has
sprung from the anthropoid ape root and has led up to man; the latter
I have designated the family of the Hominidae.

For the rest, there are, as we have said, various possible ways of
constructing the narrower genealogy within the limits of this branch
including men and apes, and these methods will probably continue to
change with the accumulation of new facts. Haeckel himself has
modified his genealogical tree of the Primates in certain details
since the publication of his _Generelle Morphologie_ in 1866, but its
general basis remains the same.[123] All the special genealogical
trees drawn up on the lines laid down by Haeckel and Darwin--and that
of Dubois may be specially mentioned--are based, in general, on the
close relationship of monkeys and men, although they may vary in
detail. Various hypotheses have been formulated on these lines, with
special reference to the evolution of man. _Pithecanthropus_ is
regarded by some authorities as the direct ancestor of man, by others
as a side-track failure in the attempt at the evolution of man. The
problem of the monophyletic or polyphyletic origin of the human race
has also been much discussed. Sergi[124] inclines towards the
assumption of a polyphyletic origin of the three main races of man,
the African primitive form of which has given rise also to the
gorilla and chimpanzee, the Asiatic to the Orang, the Gibbon, and
_Pithecanthropus_. Kollmann regards existing human races as derived
from small primitive races (pigmies), and considers that _Homo
primigenius_ must have arisen in a secondary and degenerative manner.

But this is not the place, nor have I the space to criticise the
various special theories of descent. One, however, must receive
particular notice. According to Ameghino, the South American monkeys
(_Pitheculites_) from the oldest Tertiary of the Pampas are the forms
from which have arisen the existing American monkeys on the one hand,
and on the other, the extinct South American Homunculidae, which are
also small forms. From these last, anthropoid apes and man have, he
believes, been evolv