The tribe, speaking of the Australians, for instance, is a large aggregate of friendly or not hostile human groups, occupying a territory of perhaps a hundred square miles, and holding councils and meetings for social and religious purposes. It is so far ‘endogamous’ that its members _may_ marry within it--that is to say, it is no more endogamous than the parish of Marylebone. An Urabunna man, a man of the Urabunna tribe, may marry an Urabunna woman--if no special native law interferes. He may also at pleasure marry, out of his tribe, say a woman of the neighbouring Arunta tribe, again, if no special law bars the arrangement. So far the tribe, the large local aggregate of groups, stands indifferent. But, within the tribe, there are laws barring marital intercourse. First, each tribe is usually composed of two ‘primary exogamous divisions,’ or ‘phratries,’ so called; in the case of some tribes the phratries are named; for example, _Matthurie_ and _Kirarawa_. Every man and woman, in such tribes, is either a Matthurie or a Kirarawa, and can only marry into the opposite division, and the children follow the name of the mother. These two divisions are called ‘primary classes’ by some students; ‘phratrias’ (from the Greek: Φρατρία) by others; ‘sub-tribes’ by others; or, again, ‘moieties,’ or ‘groups.’ I shall, in each instance, use the term (‘class,’ ‘phratria,’ ‘moiety,’ ‘primary exogamous division,’ ‘group,’ and the like) employed by the author whose opinion I am discussing, though I prefer ‘phratry,’ as ‘class’ has another significance; so has ‘group,’ &c. Again, the tribe contains a number of totem kindreds (often called ‘clans’ or _gentes_, rather at random), that is, of sets of kin deriving their names from _totems_, plants, animals, or other objects in nature. To the possible origin of Totemism we return in a separate section. No Urabunna man may marry a woman of his own ‘phratry,’ nor of his own _totem_, and the children inherit the phratry and totem names from the mother. Finally, there are sets of relationships, roughly indicating, it would seem, seniority by generations, and degrees of actual or supposed kindred. Within many of these, which I shall style ‘classes’ (they have other terms applied to them), marriage is forbidden. Thus there are bars of three several sorts on the intermarrying of an Urabunna man with an Urabunna woman. In a way, there are three grades of exogamous prohibitions.