ust be regarded as a primate mammalian vertebrate.

* * * * *

The comparative study of the human organism as a structural type has now
been narrowed down to a review of the various members of the order of
primates. It is the duty of science to arrange these organisms according
to the minor differences beneath the agreements in major qualities, and to
show how they are related in an order of evolution. It will appear, when
this is done, that the supreme place is given to the human species on
account of four and only four characteristics; these are (1) an entirely
erect posture, (2) greater brain development, (3) the power of articulate
speech, and (4) the power of reason. As we are treating the human body as
a subject for comparative structural study, the third and fourth
characters do not concern us here; but it is well to point out that they
depend entirely upon the second, and that they are the functional
concomitants of the improved type of brain belonging to the highest type.
Two characters remain, and in both cases it is significant that
differences in degree only are to be found by even the closest analysis.
The human brain is the same kind of brain that lower primates possess; its
structure is unique in no general respect. And as regards the
first-mentioned character, comparative anatomy shows, in the first place,
that this also is something differing only in degree, and in the second
place, that it is due directly to the development of the brain. For these
reasons a survey of the various members of the order of primates must deal
largely with the progressive elaboration of the brain and the entailed
effects of this enlargement.

The order of primates is subdivided as follows :--

Sub-order 1. _PROSIMII_. Lemurs.
Sub-order 2. _ANTHROPOIDEA_.
Family 1. _Hapalidae_. The marmosets.
Family 2. _Cebidae_. The American or tailed monkeys.
Family 3. _Cercopithecidae_. The baboons.
Family 4. _Simiidae_. The true apes.
Family 5. _Hominidae_. The human species. Primates

Each one of these subdivisions is interesting in its own way, either
because its members depart from the typical condition of the whole order
in some respects, or because of some character that foreshadows and leads
to a more developed element of the animals placed in the higher sections.

The lemurs are small animals very much like squirrels in their general
form and in their tree-climbing habits. They live n