[1] The survey presented in this and in the following section aims to give only a general outline of the relations between totemism and tribal organization, as based particularly on several tribes of Central Australia. For a more detailed account of the conditions and of their probable interpretation, I would refer to a paper on "Totemism and Tribal Organization in Australia," published, in 1914, in _Anthropos_, an international journal. 4. THE ORIGIN OF EXOGAMY. Though the dual organization of the tribe seems to admit of a comparatively simple and easy explanation, the totemic exogamy which is closely bound up with it offers great difficulties. As we have already seen, totemic exogamy is characterized by the fact that a member of one specific clan, or of a totem group belonging to the clan, may enter into marriage only with a member of another clan or totem group. This restriction of the marriage relationship is generally known as 'exogamy,' a term first introduced by the Scottish ethnologist and historian, McLennan. In order to distinguish this custom from later regulations of marriage, such, for example, as exist in present law, in the prohibition of the union of relatives by blood or by marriage, we may call it more specifically 'totemic exogamy.' Totemic exogamy clearly represents the earliest form of marriage restriction found in custom or law. The phenomena bound up with it may be regarded as having arisen either contemporaneously with the first division of the tribe or, at any rate, soon thereafter, for some of the Australian and Melanesian tribes practise exogamy even though they have not advanced beyond a twofold division of the tribe. On the other hand, the primitive horde of the pretotemic age remains undivided, and, of course, shows no trace of exogamy. True, marriages between parents and children seem to have been avoided as early even as in pretotemic times. But this could hardly have been due to the existence of firmly established norms of custom. Such norms never developed except under the influence of totemic tribal organization, and they are closely related to its various stages of development. Taking as the basis of consideration the above-mentioned conditions in Australia, where an approximate regularity in the successive stages of this development is most clearly in evidence, we may distinguish particularly _three_ main forms of exogamy. The first is the simplest. If we designate the two divisions of the tribe between which exogamic relations obtain, by A and B, and the various subgroups of A by _l, m, n, o,_ and of B by _p, q, r, s,_ we have, as this simplest form, _unlimited exogamy_. It corresponds to the following schema:-- I. _Unlimited Exogamy._ A B _l m n o p q r s_ |______________________________|