ribal sister may be given in exchange for a
wife. From this it follows that, theoretically at any rate, the
contracting parties are corporations rather than individuals, and in
this case the death of the individual on whose behalf the transaction
has been effected does not extinguish the proprietary rights acquired by
handing over a woman, standing in the relation of sister to the one
corporation, in exchange for another woman standing in the relation of
sister to the other corporation.

If this solution is correct, it is unnecessary to go into the
complicated question of the relation of brother-inheritance to matriliny
and patriliny. For it is by no means clear that it is an exemplification
of the former rather than the latter principle. It may, of course, be
argued that brothers succeed as children of the same mother; but against
this must be set the fact that they are also children of the same
father; for uncertain paternity can only be a _vera causa_ where
_pirrauru_ and similar customs are found; and even here the pre-eminence
of the primary husband might well be held to determine the legal
paternity of the children, which is, of course, especially in Africa, a
matter of potestas rather than procreation. However this may be, the
position of the widow does not appear to invalidate the guardianship
origin of matriliny.

We now turn to the question of why male tends to take the place of
female descent. The possible factors are (1) authority in the family,
(2) the rise of chieftainship and inheritance generally, and (3) the
organisation of the family group. Of the authority of father or mother
over the children, there is not much trace in Australia except in the
most youthful period of the pre-adult life. It is for example
exceptional for a parent to correct a child. As to who decides in cases
of infanticide we have unfortunately too little information to be able
to generalise. Only in one important step--that of betrothal--have we
anything like adequate information, and the interrelations between rule
of descent and potestas are found to be in this case sufficiently clear,
though it is not clear on what principle it is decided _who_ shall
exercise the right.

Taking first tribes with matrilineal descent, we find that the Barkinji,
the Wakelbura, the Dieri, and in some cases the Wollaroi, assign the
right of betrothal to the mother or mother's brother[19]. In other
cases, transitional forms, the father, his elder br