assed." Darwin
carries this further by stating "that resemblances in several
unimportant structures, in useless and rudimentary organs, or not now
functionally active, or in an embryological condition, are by far the
most serviceable for classification."[121] It has also to be
remembered that _numerous_ separate points of agreement are of much
greater importance than the amount of similarity or dissimilarity in a
few points.

The hypotheses as to descent current at the present day may be divided
into two main groups. The first group seeks for the roots of the human
race not among any of the families of the apes--the anatomically
nearest forms--nor among their very similar but less specialised
ancestral forms, the fossil representatives of which we can know only
in part, but, setting the monkeys on one side, it seeks for them lower
down among the fossil Eocene Pseudo-lemuridae or Lemuridae (Cope), or
even among the primitive pentadactylous Eocene forms, which may
either have led directly to the evolution of man (Adloff), or have
given rise to an ancestral form common to apes and men (Klaatsch,[122]
Giuffrida-Ruggeri). The common ancestral form, from which man and apes
are thus supposed to have arisen independently, may explain the
numerous resemblances which actually exist between them. That is to
say, all the characters upon which the great structural resemblance
between apes and man depends must have been present in their common
ancestor. Let us take an example of such a common character. The bony
external ear-passage is in general as highly developed in the lower
Eastern monkeys and the anthropoid apes as in man. This character
must, therefore, have already been present in the common primitive
form. In that case it is not easy to understand why the Western
monkeys have not also inherited the character, instead of possessing
only a tympanic ring. But it becomes more intelligible if we assume
that forms with a primitive tympanic ring were the original type, and
that from these were evolved, on the one hand, the existing New World
monkeys with persistent tympanic ring, and on the other an ancestral
form common to the lower Old World monkeys, the anthropoid apes and
man. For man shares with these the character in question, and it is
also one of the "unimportant" characters required by Darwin. Thus we
have two divergent lines arising from the ancestral form, the Western
monkeys (Platyrrhine) on the one hand, and an ancest