and it is clearly more reasonable on other grounds to suppose
that these regulations are of independent origin. But we know the
eight-class rule to have arisen from a division within a generation,
which the Dieri rule is not. Therefore the latter must be sporadic.

The same is probably true of the Urabunna, but here our information is
very scanty and the precise working of the rules is far from clear. What
happens is that an elder brother (A) of a woman (B) marries an elder
sister (D) of a man (C); the daughter of this elder sister (D) is the
proper mate for the son of the younger sister (B) of her husband; this
younger sister's husband is the younger brother, C. Now the term elder
brother, elder sister, does not seem to refer to age; the rule appears
to be--once an elder brother, always an elder brother from generation to
generation.

We learn from Spencer and Gillen, that all the women of a generation in
the one phratry, and presumably within the right totem only, are to a
man either _nupa_ (=marriageable) or _apillia_. In the case given by Dr
Howitt the younger sister is _nupa_ to the younger brother, the elder to
the elder brother; but we do not learn how elder and younger are
distinguished, if it is not by descent. Apparently it cannot be by
descent, however; for we find that the son of the younger brother and
sister marries the daughter of the elder brother and sister. As to what
would happen if the younger brother and sister have a daughter, the
elder a son, we have no information; but apparently they cannot marry.
Such a daughter must find the son of two people who stand to her father
and mother as they stood to A and D.

From this example it is clear that the boundaries of the _nupa_ and
_apillia_ groups are not fixed in a given group of women; it is not
possible to divide the women and the men into elder brothers and sisters
on the one hand, younger brothers and sisters on the other. But if this
is the case, we are quite in the dark as to the meaning of the marriage
regulations.

One thing however seems certain; viz., that the Urabunna regulations do
not give the same result as the four-class regulations. With them the
division is within the generation. There is no class of women, who, with
their descendants, are the normal spouses of a class of men, with their
descendants. That being so, the Urabunna case can hardly throw light on
the genesis of the four-class system.

Among the Urabunna, however, like t