The results presented in the table show considerable individual
variation in the femoro-cranial index, by reason of which there is
some irregularity of alignment of the cases. This is especially true
in regard to the capacity, which in this small series shows little
regularity or evidence of conformity with the aforementioned general
rule of increase of the size of the head with stature. The tallest of
the eight females had one of the smallest heads, and the man with the
largest brain was not even of average height. However, there is no
doubt that if the series of skulls was considerably larger, the usual
progression, showing gradual increase in the size of the brain with the
height of the body, would be apparent.
The femoro-cranial index progresses much more regularly than the
capacity, and shows another well-known fact, also common to all human
races, namely, that while the absolute size of the brain enlarges in
proportion to the stature, its relative dimensions with reference to
stature diminish as the latter increases; so that while the tall man
or woman may be expected to have an absolutely larger brain than the
average of his group, relatively to his stature he will have less brain
matter than the short individuals of the same group.
The averages in the preceding table are interesting in another
particular—i. e., the difference in the value of the femoro-cranial
index in the two sexes. Both the former records of the Louisiana
crania and those of the Munsee now presented show these indexes to be
perceptibly lower in the females than in the males. The superiority in
this respect among the male crania is seen not only in the averages,
but practically throughout the records, seven of the eight indexes in
the females being below the minimum of the indexes in the males. It
seems evident that among the Indians the brain substance in the females
is not only absolutely smaller than in the males, but is also somewhat
smaller for each centimeter of stature, so that men of the same height
as the women would still show an advantage in this particular. This
advantage is not necessarily connected with mentality, but may be due
to the greater muscularity of the males.
As to the value of the femoro-cranial index in different tribes, we can
as yet say nothing positive. The indications are that if differences
exist, they are not of a very pronounced character.