Both forms of exogamy, the unlimited and the limited, observe the same law with respect to the group affiliation of children. If, as universally occurs in Australia, A and B are clans having exogamous relations, and _l, m, n, o, p,..._ are totem groups within these clans, then, if maternal descent prevails, the children remain both in the clan and in the totem of the mother; in the case of paternal descent, they pass over to the clan and to the totem of the father. Of these modes of reckoning descent, the former is dominant, and was everywhere, probably, the original custom. One indication of this is the connection of paternal descent with other phenomena representing a change of conditions due to external influences--the occurrence of the same totem groups, for example, in the two clans, A and B, that enjoy exogamous relations. The latter phenomenon is not to be found under the usual conditions, represented by diagrams I and II. In the case of unlimited exogamy (I), no less than in that of limited exogamy, we find that if, for example, maternal descent prevails, and, the mother belongs to clan B and to totem group _r_, the children likewise belong to this group _r_. This condition is much simplified in the case of the American Indians. With them, totem group and clan coincide, the totem names having become the names of the clans themselves. The particular totem groups, _l, m, n, o, p,..._ do not exist. Exogamous relations between clans A and B consist merely in the fact that a man of the one clan is restricted in marriage to women of the other clan. Wherever maternal descent prevails, as it does, for example, among the Iroquois, the children are counted to the clan of the mother; in the case of paternal descent, they belong to the clan of the father. In the Australian system, however, which distinguishes clan and totem, and therefore, as we may suppose, still exemplifies, on the whole, an uninterrupted development, we find also a _third_ form of exogamous relationship. This last form of exogamy seems to be the one which is most common in Australia, whereas, of course, it has no place in the pure clan exogamy of the American Indians. The system indicated in diagram II, in which children belong directly to the clan of the mother in maternal descent and to that of the father in paternal descent, may be designated as limited exogamy with direct maternal or paternal descent. There developed from this a third system, in which, while the children are counted to the _clan_ of the parent who determines descent, they nevertheless become members of a different totem group. Thus arises a limited exogamy with _indirect_ maternal or paternal descent, as represented in diagram III. III. _Limited Exogamy, with Indirect Maternal or Paternal Descent._ A B _l m n o p q r s_ |____________________________|~